Tool driver with reaction torque sensor for use in robotic surgery

ABSTRACT

A tool driver for use in robotic surgery includes a base configured to couple to a distal end of a robotic arm, and a tool carriage slidingly engaged with the base and configured to receive a surgical tool. In one variation, the tool carriage may include a plurality of linear axis drives configured to actuate one or more articulated movements of the surgical tool. In another variation, the tool carriage may include a plurality of rotary axis drives configured to actuate one or more articulated movements of the surgical tool. Various sensors, such as a capacitive load cell for measuring axial load, a position sensor for measuring linear position of the guide based on the rotational positions of gears in a gear transmission, and/or a capacitive torque sensor based on differential capacitance, may be included in the tool driver.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of pending U.S. patent applicationSer. No. 15/803,665 filed Nov. 3, 2017, which claims priority to U.S.Patent Application Ser. No. 62/417,205, filed on Nov. 3, 2016, which isincorporated by this reference herein in its entirety.

TECHNICAL FIELD

This disclosure relates generally to robotic or robotic-assisted systemsand, more particularly, to tool drivers for robotic or robotic-assistedsurgical systems.

BACKGROUND

Minimally-invasive surgery (MIS), such as laparoscopic surgery, involvestechniques intended to reduce tissue damage during a surgical procedure.For example, laparoscopic procedures typically involve creating a numberof small incisions in the patient (e.g., in the abdomen), andintroducing one or more tools and at least one camera through theincisions into the patient. The surgical procedures are then performedby using the introduced tools, with the visualization aid provided bythe camera.

Generally, MIS provides multiple benefits, such as reduced patientscarring, less patient pain, shorter patient recovery periods, and lowermedical treatment costs associated with patient recovery. However,standard MIS systems have a number of drawbacks. For example,non-robotic MIS systems place higher demands on the surgeon, in partbecause they require surgeons to indirectly manipulate tissue via toolsin a manner that may not be natural. Conventional robotic systems, whichmay include one or more tool drivers positioned with a robotic arm andremotely operated to manipulate tools based on commands from anoperator, may provide many benefits of MIS while reducing demands on thesurgeon. However, such tool drivers tend to be large and difficult tomaneuver effectively with robotic arms. Thus, it is desirable to havetool drivers for robotic-assisted surgical systems that are more compactand efficient.

SUMMARY

Generally, in some variations, a tool driver for use in robotic surgeryincludes a base configured to couple to a distal end of a robotic arm,where the base includes a longitudinal track, and a tool carriageslidingly engaged with the longitudinal track and configured to receivea surgical tool, where the tool carriage includes at least one linearaxis drive assembly. The linear axis drive assembly may include, forexample, a motor including a motor shaft, a gear transmission coupled tothe motor, a threaded shaft having a proximal shaft end coupled to thegear transmission and a distal shaft end providing a linear axis driveoutput, and an axially-movable guide mounted on the threaded shaft. Thethreaded shaft may, in some variations, be a ball screw and the guidemay be or include a ball screw nut engaged with the ball screw. Thelinear axis drive output may be configured to actuate one or morearticulated movements of the surgical tool. In some variations, the toolcarriage may further include at least one rotary axis drive assemblyconfigured to rotate the surgical tool around a tool axis. For example,the tool carriage may include two rotary axis drive assembliesconfigured to antagonistically rotate the surgical tool around the toolaxis.

In some variations, the tool driver may include a capacitive load cellhaving characteristics making it suitable for use in a compact area. Forexample, the load cell may be disposed on the threaded shaft between theguide and the distal shaft end and configured to measure axial load onthe threaded shaft. The capacitive load cell may include a firstconductive plate fixed relative to the guide and a second conductiveplate fixed relative to the threaded shaft. The capacitive load cellmay, for example, include a housing having a first housing region and asecond housing region axially movable relative to the first housingregion. For example, the second housing region may be radially connectedto the first housing region (e.g., the radial connection may allow forrelative axial movement between the first and second housing regions).The first housing region may be coupled to the guide and the secondhousing region may be coupled to the threaded shaft. In some variations,the first conductive plate may be coupled to the first housing regionand the second conductive plate may be coupled to the second housingregion.

Additionally or alternatively, in some variations, the tool driver mayinclude a position sensor integrated with or adjacent to the geartransmission, such that the position sensor is compact and utilizesinformation from parts existing in the gear transmission in order tomeasure axial position of the guide. For example, the gear transmissionmay include a first gear having a first number of teeth and a secondgear having a second number of teeth different from the first number ofteeth, and the tool driver may further include a position sensor formeasuring axial position of the guide based on relative rotationalpositions of the first and second gears. For example, the positionsensor may include a first rotary encoder measuring rotational positionof the first gear, and a second rotary encoder measuring rotationalposition of the second gear. In some variations, the first gear may becoupled to the motor shaft and the second gear may be coupled to theproximal shaft of the threaded shaft. The second gear may have moreteeth than the first gear, but alternatively the first gear may havemore teeth than the second gear. In other variations, the first andsecond gears whose relative rotational positions are measured may be inany suitable portion of the gear transmission.

Generally, different variations of a tool driver may include at leastone linear axis drive assembly including a capacitive load cell similarto that described above. The linear axis drive assembly may beconfigured to actuate one or more articulated movements of a surgicaltool. For example, generally, a tool driver for use in robotic surgerymay include at least one linear axis drive assembly including a threadedshaft and a guide mounted on the threaded shaft, and a capacitive loadcell disposed on the threaded shaft and configured to measure axial loadon the threaded shaft.

The capacitive load cell may include characteristics making it suitablefor use in a compact area. For example, the load cell may be disposedbetween the guide and a distal end of the threaded shaft. In somevariations, the capacitive load cell may include a first conductiveplate referenced to the guide and a second conductive plate referencedto the threaded shaft. The capacitive load cell may include a housinghaving a first housing region and a second housing region axiallymovable relative to the first housing region. The first housing regionmay be coupled to the guide and the second housing region may be coupledto the threaded shaft. The second housing region may, for example, beradially connected to the first housing region. The first conductiveplate may be coupled to the first housing region and the secondconductive plate may be coupled to the second housing region. In somevariations, the load cell may be disposed between the guide and a distalend of the threaded shaft.

Furthermore, different variations of a tool driver may include at leastone linear axis drive assembly including a position sensor similar tothat described above. The linear axis drive assembly may be configure toactuate one or more articulated movements of a surgical tool. Forexample, generally, a tool driver for use in robotic surgery may includeat least one linear axis drive assembly including a motor including amotor shaft, a gear transmission coupled to the motor shaft, and anaxially movable guide driven by the motor via the gear transmission. Thegear transmission may include a first gear having a first number ofteeth and a second gear having a second number of teeth different fromthe first number of teeth. In these variations, the tool driver mayfurther include a position sensor for measuring linear position of theguide based on the rotational positions of the first and second gear.

The position sensor may be integrated with or adjacent to the geartransmission, such that the position sensor is compact and utilizesinformation from parts existing in the gear transmission in order tomeasure axial position of the guide. For example, the position sensormay include a first rotary encoder measuring rotational position of thefirst gear, and a second rotary encoder measuring rotational position ofthe second gear. The position sensor may measure linear position of theshaft based on the relative rotational positions of the first and secondgears (e.g., the rotational position of the first gear relative to therotational position of the second gear). In some variations, the firstgear may be coupled to the motor shaft and the second gear may becoupled to the proximal shaft of the threaded shaft. The second gear mayhave more teeth than the first gear, but alternatively the first gearmay have more teeth than the second gear. In other variations, the firstand second gears whose relative rotational positions are measured may bein any suitable portion of the gear transmission.

Generally, a tool driver for use in robotic surgery may include at leastone rotary axis drive for actuating one or more articulated movements ofa surgical tool, where the rotary axis drive includes a motor and atorque sensor included to the motor (e.g., for measuring reaction torqueduring actuation by the rotary axis drive).

In some variations, the torque sensor may include a torsional springstructure having a proximal spring portion and a distal spring portion,a first patterned conductive surface referenced to the proximal springportion, and a second patterned conductive surface facing the firstpatterned conductive surface and referenced to the distal springportion. The first and second patterned conductive surfaces may, forexample, be disposed on first and second plates, respectively. Thetorque sensor may be configured to provide a torque measurement based atleast in part on a differential capacitance between the first and secondpatterned conductive surfaces. In some variations, the proximal springportion and the distal spring portion may be connected via a pluralityof members (e.g., one or more members that flex torsionally). One ormore stoppers (e.g., mechanical stoppers) may limit the relativerotational movement of the proximal spring portion and the distal springportion.

In these variations of a torque sensor with a torsional springstructure, the proximal spring portion may, for example, be coupled tothe rotary axis drive to mount the torque sensor to the rotary axisdrive. In some variations, the first and second conductive surfaces maybe directly or indirectly coupled to the torsional spring structure suchthat the first patterned conductive surface (referenced to the proximalspring portion) is proximal to the second patterned conductive surface(referenced to the distal spring portion). Alternatively, in othervariations, the first and second conductive surfaces may be directly orindirectly coupled to the torsional spring structure such that the firstpatterned conductive surface (referenced to the proximal spring portion)is distal to the second patterned conductive surface (referenced to thedistal spring portion).

In some variations, the torque sensor may include a first patternedconductive surface and a second patterned conductive surface, where thefirst and second patterned conductive surfaces are rotatable relative toeach other. The torque sensor may be configured to provide a torquemeasurement based at least in part on differential capacitance betweenthe first and second patterned conductive surfaces. In some variations,the first and second patterned conductive surfaces may be disposed onfirst and second plates, respectively, and the torque sensor may includea frame including a proximal frame portion coupled to the first plateand a distal frame portion coupled to the second plate. The first platemay be proximal to the second plate. Alternatively, the first plate maybe distal to the second plate. The proximal frame portion and the distalframe portion may be connected via at least one member (e.g., one ormore members that flex torsionally). One or more stoppers (e.g.,mechanical stoppers) may limit the relative rotational movement of theproximal spring portion and the distal spring portion.

In various torque sensor variations, at least one of the first andsecond patterned conductive surfaces may include a first plurality ofconductive strips and a second plurality of conductive strips. Forexample, the surface with the first and second groups of conductivestrips may be considered an “active” conductive surface. The firstplurality of conductive strips may be interconnected (e.g., via at leastone conductive trace) to form a first signal channel, and the secondplurality of conductive strips may be interconnected (e.g., via at leastone conductive trace) to form a second signal channel. In somevariations, the first plurality of conductive strips and the secondplurality of conductive strips may be arranged in an alternatingpattern.

Additionally, at least one of the first and second patterned conductivesurfaces may include a third plurality of conductive strips facing thefirst and the second pluralities of conductive strips. The thirdplurality of conductive strips may be interconnected to form a commonelectrical ground. For example, the surface with the third plurality ofconductive strips may be considered a “ground” conductive surface facingthe “active” conductive surface.

Generally in some variations, a tool driver for use in robotic surgerymay include at least one rotary axis drive including a rotary outputshaft configured to actuate one or more articulated movements of asurgical tool, where the rotary axis drive includes a motor including amotor shaft, a gear transmission at least partially disposed within themotor shaft where the gear transmission (e.g., a planetary gear train)include an input coupled to the motor shaft and an output shaft coupledto the rotary output shaft, and a torque sensor disposed between thegear transmission and a distal end of the rotary output shaft. In somevariations, the tool driver may include a base configured to couple to adistal end of a robotic arm, and the tool carriage may be slidinglyengaged with the base.

In some variations, the rotary axis drive may include a cable carryingsignals (e.g., at least from the torque sensor), where the cable wrapscircumferentially at least partially around the rotary axis drive,around an axis of rotation of the rotary shaft. By following the path oftorsional motion of the rotary axis drive (e.g., as the result ofreaction torque during actuation), such circumferential wrapping mayreduce undesirable strain or other loads on the cable. For example, thecable may wrap at least about 45 degrees around the rotary axis drive,at least 90 degrees around the rotary axis drive, or at least about 135degrees around the rotary axis drive.

In some variations, the rotary output shaft may be configured to rotatearound and axially translate along an axis. In such variations, a rotaryencoder may be configured to measure an axial position of the rotaryoutput shaft along the axis (additionally or alternatively to beingconfigured to measure rotational position of the rotary output shaft).

A tool driver may include a plurality of such rotary axis drives. Insome variations, one or more of the rotary drives may be mounted to atool carriage only a distal portion of the rotary axis drive (e.g., andotherwise may be free-standing, or unsupported by additional frameworkstructures, etc.).

Generally, in some variations, a tool driver for use in robotic surgerymay include a base configured to couple to a distal end of a roboticarm, a tool carriage slidingly engaged with the base and configured toreceive a surgical tool, where the tool carriage includes a plurality ofrotary axis drive modules. The rotary axis drive modules may beconfigure to actuate one or more articulated movements of the surgicaltool, and may be arranged in the tool carriage in a modular, scalablearray. In some variations, each rotary axis drive module may be mountedto the tool carriage only at a distal portion of the rotary axis drivemodule.

The plurality of rotary axis drive modules may be arranged in a regularrepeating pattern in the tool carriage. Furthermore, the tool driver mayinclude a plurality of circuit board modules, where each circuit boardmodule is associated with at least one rotary axis drive module. Theplurality of circuit board modules may be arranged in a second regularrepeating pattern. In some variations, the plurality of circuit boardmodules may be interconnected via a cable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of one exemplary variation of a tooldriver on a robotic arm manipulator.

FIGS. 2A and 2B are perspective views of an exemplary variation of atool driver. FIG. 2C is a side view of the tool driver of FIGS. 2A and2B showing the tool carriage in two different positions.

FIGS. 3A and 3B are front perspective and rear perspective views,respectively, of a base in an exemplary variation of a tool driver.FIGS. 3C and 3D are detailed side and top views of a proximal mountingplate on the base depicted in FIGS. 3A and 3B. FIG. 3E is a partialperspective view of a distal end of the base depicted in FIGS. 3A and3B. FIG. 3F is a longitudinal cross-sectional view of the region of thebase marked 3F in FIG. 3E.

FIG. 4A is a perspective view of one variation of a tool carriage havingcombined linear axis drives and rotary axis drives. FIG. 4B is aperspective view of a partially disassembled version of the toolcarriage depicted in FIG. 4A. FIG. 4C is a perspective view of a rotaryaxis drive in the tool carriage depicted in FIG. 4B. FIG. 4D is aperspective view of a left side of the tool carriage depicted in FIG.4B. FIG. 4E is a perspective view of a version of the tool carriagedepicted in FIG. 4B, with the addition of a top housing plate.

FIG. 5A is an illustrative schematic of a linear axis drive in onevariation of a tool carriage. FIGS. 5B-5D are a partial cutaway view, abottom side view, and a perspective view, respectively, of the linearaxis drive gears and encoders in the variation of the tool carriagedepicted in FIG. 5A.

FIGS. 6A-6D are illustrative schematics of one variation of a multi-turnabsolute encoder sensor.

FIG. 7A is a perspective view of a compact load cell, such as for use ina linear axis drive in one variation of the tool carriage. FIG. 7B is alongitudinal cross-sectional view of the load cell depicted in FIG. 7A.FIG. 7C is an illustrative schematic of the load cell depicted in FIG.7A, implemented in one variation of a linear axis drive. FIGS. 7D and 7Eare exploded perspective views of the load cell depicted in FIG. 7A.FIGS. 7F and 7G are perspective views of the load cell depicted in FIG.7A mounted in one variation of a linear axis drive.

FIGS. 7H and 7I are a longitudinal cross-sectional view and an explodedperspective view, respectively, of another variation of a compact loadcell including a reference capacitive plate.

FIGS. 7J and 7K are an exploded perspective view and a longitudinalcross-sectional view, respectively, of the variation of the load celldepicted in FIG. 7H for use in a linear axis drive in one variation ofthe tool carriage.

FIG. 8A is an axial cross-sectional view of a rotary axis drive in onevariation of a tool carriage. FIGS. 8B and 8C are a detailedlongitudinal cross-sectional view and a detailed perspective view,respectively, of the rotary axis drive depicted in FIG. 8A.

FIG. 9A is a perspective view of another variation of a tool driver.FIG. 9B is a perspective view of a partially disassembled version of thetool driver depicted in FIG. 9A.

FIGS. 10A and 10B are perspective views of another variation of a toolcarriage having a plurality of rotary axis drives. FIG. 10C is apartially exploded view of the tool carriage depicted in FIGS. 10A and10B. FIG. 10D is a top view of the tool carriage depicted in FIGS. 10Aand 10B without a top housing plate. FIG. 10E is a top view of a housingbody mounted to a base of a tool driver. FIGS. 10F and 10G are a sidetranslucent view and a front translucent view, respectively, of the toolcarriage depicted in FIGS. 10A and 10B mounted to a base of a tooldriver.

FIG. 11A is a perspective view of one variation of a rotary axis drivein another variation of a tool driver. FIG. 11B is a longitudinalcross-sectional view of the rotary axis drive depicted in FIG. 11A.FIGS. 11C and 11D are schematics of a load cell connector ring in therotary axis drive depicted in FIG. 11A. FIGS. 11E and 11F are schematicillustrations of variations of load cell placement in the rotary axisdrive depicted in FIG. 11A.

FIG. 12A is a perspective view of a side-mounted encoder board. FIG. 12Bis a schematic illustration of an encoder ring magnet and a side-mountedencoder sensor.

FIGS. 13A-13E are illustrative schematics depicting an exemplaryassembly process for one variation of a tool carriage with a pluralityof rotary axis drives.

FIGS. 14A-14C are longitudinal cross-sectional views of one variation ofa rotary axis drive with a compliant motor coupling disc.

FIG. 15A is a longitudinal cross-sectional view of one variation of arotary axis drive with a planetary gear train at least partiallydisposed in a motor in the rotary axis drive. FIG. 15B is an axialcross-sectional view of the rotary axis drive depicted in FIG. 15A.

FIGS. 16A-16C are top, side, and perspective views, respectively, of onevariation of a tool carriage having rotary axis drives withcycloid-based transmissions. FIG. 16D is a top view of a rotary axisdrive with a cycloid-based transmission. FIG. 16E is a longitudinalcross-sectional view of the rotary axis drive depicted in FIG. 16D,taken along the line A-A.

FIGS. 17A and 17B are perspective and longitudinal cross-sectionalviews, respectively, of one variation of a rotary axis drive with anintegrated reaction torque sensor assembly.

FIG. 18A is an exploded view of a partial assembly of one variation of atool carriage configured to include multiple instances of the rotaryaxis drive depicted in FIGS. 17A and 17B.

FIG. 18B is a cutaway perspective view of the partial assembly depictedin FIG. 18A.

FIGS. 19A and 19B are a longitudinal cross-sectional view and anexploded perspective view, respectively, of another variation of arotary axis drive with an integrated torque sensor assembly and thermalmanagement features.

FIGS. 20A and 20B are a longitudinal cross-sectional view and aperspective view, respectively, of another variation of a rotary axisdrive with an integrated torque sensor assembly and an input rotaryencoder. FIG. 20C is a perspective view of the input rotary encoder inthe rotary axis drive depicted in FIG. 20A.

FIG. 21A is a schematic illustration of a wireless tool driverinterface. FIG. 21B is a schematic illustration of a wireless toolinterface.

FIGS. 22A and 22B are perspective assembly and exploded views,respectively, of a capacitive absolute rotary encoder. FIGS. 22C and 22Dare examples of conductive plates in the encoder depicted in FIGS. 22Aand 22B. FIG. 22E is a plot of capacitive signals mapped to output anglefor one exemplary variation of the encoder depicted in FIGS. 22A and22B.

FIG. 23A is an exploded view of one variation of a torque sensorassembly. FIG. 23B is a schematic illustration of first and secondconductive plates in the torque sensor assembly depicted in FIG. 23A.FIG. 23C is a detailed view of the overlap between the first and secondplates in the torque sensor assembly depicted in FIG. 23A. FIG. 23D is aperspective view of a frame in the torque sensor assembly depicted inFIG. 23A. FIGS. 23E and 23F are longitudinal cross-sectional views oftwo variations of the reaction torque sensor assembly implemented on arotary axis drive, such as for a tool carriage.

FIG. 24A is a perspective longitudinal cross-sectional view of acombined sensor assembly including one variation of a reaction torqueassembly combined with one variation of a capacitive absolute rotaryencoder. FIG. 24B is a top view of the combined sensor assembly depictedin FIG. 24A.

FIGS. 25A and 25B are perspective and cross-sectional views,respectively, of a rotary axis drive with another variation of a torquesensor.

FIG. 26A is a perspective view of a frame in the torque sensor assemblydepicted in FIGS. 25A and 25B. FIG. 26B is a side cross-sectional viewof the frame depicted in FIG. 26A with a conductive plate. FIG. 26C is aperspective cross-sectional view of the torque sensor assembly depictedin FIGS. 25A and 25B.

FIGS. 27A and 27B are detailed schematics of conductive regions on aground conductive plate and an active conductive plate in a torquesensor. FIG. 27C is a detailed schematic of overlaid conductive regionsof the ground and active conductive plates depicted in FIGS. 27A and27B.

FIG. 28A is a perspective view of another variation of a torque sensor.FIG. 28B is a perspective view of a frame in the torque sensor depictedin FIG. 28A. FIGS. 28C and 28D are exploded views of the torque sensordepicted in FIG. 28A.

FIGS. 29A and 29B are overall and detailed views of one variation of aground conductive plate in a torque sensor.

FIGS. 30A and 30B are overall and detailed views of one variation of anactive conductive plate in a torque sensor.

FIGS. 31A and 31B are overall and detailed views of another variation ofan active conductive plate in a torque sensor.

FIGS. 32A and 32B are perspective and side views of another variation ofa torque sensor with an angled electronics mount portion.

FIGS. 33A and 33B are exploded views of another variation of a torquesensor with a radially inward-projecting electronics mount portion.

FIG. 34 is a perspective view of another variation of a tool driver witha plurality of rotary axis drives.

FIG. 35 is a detailed perspective view of part of the tool driverdepicted in FIG. 34.

FIG. 36 is a detailed top view of part of the tool driver depicted inFIG. 34.

FIGS. 37A and 37B are cross-sectional and perspective cross-sectionalviews, respectively, of one variation of a rotary axis drive in a tooldriver.

FIGS. 38A-38E are schematic illustrations of various assembly states ofa modular, scalable variation of a tool driver.

DETAILED DESCRIPTION

Non-limiting examples of various aspects and variations of the inventionare described herein and illustrated in the accompanying drawings.

Overview

Generally, a robotic or robotic-assisted surgical system (e.g., toenable a minimally-invasive surgical procedure) may include one or morerobotic arms for manipulating surgical tools, such as duringminimally-invasive surgery. For example, as shown in the exemplaryschematic of FIG. 1, a robotic assembly 100 may include a robotic arm110 and a tool driver 120 generally attached to a distal end of therobotic arm 110. A cannula 130 coupled to the tool driver 120 maytelescopically receive a surgical instrument or tool 150. Furthermore,the robotic arm 110 may include a plurality of links that are actuatedso as to position and orient the tool driver 120.

For use in a surgical procedure, the robotic arm 110 may be mounted toan operating table on which a patient lies (or on a cart, ceiling,sidewall, etc. near the patient). To create a port for enablingintroduction of a surgical tool into the patient, a trocar assembly(typically a cannula 130 and obturator) may be at least partiallyinserted into the patient through an incision or entry point in thepatient (e.g., in the abdominal wall). After the cannula is placed inthis manner (and the obturator is removed), the robotic arm 110 maymaneuver the tool driver 120 closer to the port, where the cannula 130may be coupled to the tool driver 120. Additionally, a tool 150 may becoupled to the tool driver 120 such that at least a portion (e.g., toolshaft) passes through the cannula and into the patient. The tool 150 mayhave an end effector disposed at the distal end of the tool shaft, andthe tool driver 120 may further be controlled to position and/or actuatethe tool 150, as further described herein, to perform various tasksduring a surgical procedure (e.g., cutting, grasping, etc.) inaccordance with the particular kind of end effector. Additionally, thetool 150 may be withdrawn from the port and decoupled from the tooldriver 120 to exchange with another tool, such as another tool having anend effector with different functionality.

As shown in FIGS. 2A and 2B, in one variation, a tool driver 200 mayinclude an elongated base (or “stage”) 210 including a longitudinaltrack 216 and a tool carriage 220 which is slidingly engaged with thelongitudinal track 216. The base 210 may be configured to couple to adistal end of a robotic arm such that articulation of the robotic armpositions and/or orients the tool driver 200 in space. Additionally, thetool carriage may be configured to receive a tool base 252 of a tool 250having a tool shaft 254 extending from the tool base 252 and furtherhaving an end effector (not shown) disposed at a distal end of the toolshaft. Generally, the tool carriage 220 may be configured to positionthe end effector of the tool relative to the base 210. For example, asshown in FIG. 2C, the tool carriage 220 may be actuated to a firstposition (position A) on the base 210, which positions the end effectorof the tool at a relatively proximal location such that the tool shaftextends the least amount possible beyond the end of the cannula 230.When the tool carriage 220 is located at position A, for example, thetool carriage 220 may be permitted to extend beyond the edge of the base210 (i.e., cantilevered off the base 210). Additionally, the toolcarriage 220 may be actuated to a second position (position B) on thebase 210, which positions the end effector of the tool at a relativelydistal position where the tool shaft extends the most amount possiblebeyond the end of the cannula 230. Furthermore, the tool carriage 220may be actuated along the longitudinal track 216 generally to any pointbetween a proximal position and a distal position (e.g., positions A andB depicted in FIG. 2C).

Generally, the tool carriage 220 may additionally be configured toorient and/or actuate the end effector of the tool. For example, thetool carriage 220 may enable rotation of the tool shaft around alongitudinal tool axis, thereby rotating the end effector of the toolabout the longitudinal tool axis. Additionally, the tool carriage 220may actuate specific functionalities of the end effector, such asthrough a cable system manipulated and controlled by actuated drives(e.g., linear axis drive, rotary axis drive, etc. such as thosedescribed herein). The tool carriage may include differentconfigurations of actuated drives. For example, in one variation, asshown in FIGS. 2A-2C, the tool carriage 220 may include a plurality oflinear axis drives configured via a cable system to actuate a set of oneor more articulated movements of the end effector and at least onerotary axis drive configured to rotate the tool shaft around a toolaxis. In another variation, FIGS. 9A and 9B and FIG. 34, a tool driver900 may include an elongated base 910 similar to base 210, but with atool carriage 920 that may include a plurality of rotary axis drives foractuating via a cable system a set of one or more articulated movementsof the end effector. FIG. 34 illustrates another tool driver variationwith a plurality of rotary axis drives. Additional details of variationsof tool carriages are described further below.

Base

The tool driver may include a base (or “stage”) that provides structuralsupport for the tool driver and its various components which are housedwithin a cover or housing. For example, as shown in FIGS. 3A and 3B, thebase 310 (with no housing shown, for clarity) may include at least onelongitudinal track 316 for supporting and guiding movement of the toolcarriage along a longitudinal axis of the base 310, and one or moreinterfaces such as an arm adapter 312 for coupling the base 310 to arobotic arm (or other manipulator) and an exemplary cannula adapter 314for coupling the base 310 to a cannula.

In one variation, the longitudinal track 316 may include a pair of railsmounted on a backbone member 318, as shown in FIG. 3A, which areparallel and extend along at least a portion of the length of the base310. The rails may be, for example, linear rails with linear bearings orother suitable linear guides. Other examples of longitudinal tracksinclude a single rail, three or more parallel rails, grooves, etc. Thetool carriage (not shown) may be coupled to a bracket 322 or othersuitable carriage interface that slidingly engages with the longitudinaltrack 316.

The tool driver may include a linear actuator configured to actuate thetool carriage along the longitudinal track. The linear actuator mayinclude, for example, a motor module 362, a ball screw 364 and a ballnut (not shown) that is threadingly engaged with the ball screw 364, anda series of one or more gears coupling an output of the motor module 362to the ball screw 364. As the ball screw 364 is rotated by the motormodule 362 and series of gears, the ball nut travels linearly along thebase 310. The tool carriage may be coupled to the ball nut directly orvia bracket 322 (e.g., mounted with fasteners), such that the toolcarriage travels with the ball nut. In other variations, other suitablelinear actuators (e.g., other kinds of leadscrews) may be used toactuate the tool carriage along the longitudinal track.

The motor module 362 may include a servomotor or other suitable motorand, in some variations, a gear transmission (e.g., planetary, harmonicdrive, etc.) for increasing the available torque output of the motormodule. Such a gear transmission may be coupled to an output shaft ofthe motor module in series, or integrated into the motor module (e.g.,in a rotor of the motor) similar to that described below. A proximal endof the ball screw 364 may be mounted on a proximal mounting block 391(as shown in FIGS. 3B-3D) via at least one proximal radial bearing 392.Similarly, a distal end of the ball screw 363 may be mounted on a distalmounting block 393 via at least one distal radial bearing 394 (as shownin FIG. 3F, which is a longitudinal cross-sectional view of the portionof the tool driver shown in FIG. 3E). In some variations, thelongitudinal track 316 may be omitted such that the tool carriagetravels based on the linear actuation (e.g., ball screw 364).

As shown in FIGS. 3C and 3D, the series of gears may include a motordrive gear 363 mounted to the output shaft of the motor module 362(e.g., with one or more set screws), at least one idler gear 366 engagedwith the motor drive gear 363, and a ball screw gear 365 engaged withthe idler gear 366 and mounted to the ball screw 364 (e.g., with one ormore set screws). The relative numbers of teeth on at least the motordrive gear 363 and the ball screw gear 365 may be selected to provideadditional torque increase. For example, in one exemplary variationdepicted in FIG. 3D, the ball screw gear 365 may have thirty teeth andthe motor drive gear 363 may have fifteen teeth, thereby providing agear ratio or mechanical advantage of about 2:1. In other examples, theseries of gears (at least the motor drive gear 363 and the ball screwgear 365) may have a gear ratio between about 1:1 and 5:1, between about1:1 and 4:1, between about 1:1 and 3:1, or between about 1.5:1 and2.5:1. The idler gear 366 may have any suitable number of teeth, thoughthe number of teeth may be selected to optimize the design of anabsolute multi-turn encoder (further described below) for measuringabsolute linear position of the carriage on the stage. Furthermore, adummy split gear 368 may be engaged with the first idler gear 366 andhave a similarly suitable number of teeth to optimize the design of theabsolute linear position sensor, as further described below with respectto FIGS. 6A-6D. In the exemplary variation depicted in FIG. 3D, thefirst idler gear 366 may have forty teeth and the dummy split gear 368may have 31 teeth. Additionally, an even number (two, four, etc.) ofidler gears may be included to adjust the directionality of the ballscrew for desired travel. In other variations, the idler gear 366 and/ordummy split gear 368 may be omitted such that the motor drive gear 363and the ball screw gear 365 are engaged directly with one another. Theseries of gears may be made of any suitable material, including but notlimited to metallic materials such as steel (e.g., 304 stainless steel)and plastic materials such as polyoxymethylene (e.g., DELRIN) which hashigh stiffness and low friction. The bracket 322 may be mounted to theball nut (or alternatively, the bracket may include threads so as todirectly engage the ball screw such that the bracket acts as a ball nut)with fasteners, welding, or other suitable attachment mechanism orprocess. Alternatively, the bracket 322 may be omitted, such that thetool carriage is mounted to the ball nut directly. Accordingly, when themotor module 362 provides a rotational output, the series of gears(including motor drive gear 363, idler gear 366, and ball screw gear365) are engaged and rotate to transfer the rotational output to theball screw 364. When ball screw 364 rotates, it transforms therotational motion into linear motion of the ball nut, bracket 322,and/or tool carriage (coupled to the ball nut or bracket) along the base310. Commanded rotation of the motor module 362 in a first directionresults in linear translation of the bracket 322 in one direction alongthe base 310 (e.g., in a distal direction), while commanded rotation ofthe motor module 362 in a second, opposite direction results in lineartranslation of the bracket 322 in an opposite direction along the base310 (e.g., in a proximal direction).

Various electronics for controlling aspects of the base 310 may becoupled to the backbone 318, the proximal mounting block 391, distalmounting block 393, and/or any other suitable structure on the base 310.For example, as shown in FIG. 3B, a printed circuit board 374 (PCB)including electronics for controlling the linear actuator (e.g., motormodule 362 and ball screw 364) may be coupled to the backbone member318. As another example, a PCB 372 including other electronics may becoupled to another region of the backbone member 318, or may be combinedwith the PCB 374. Additionally, one or more cables 376 (e.g., flexcircuits, ribbon cables) for transmitting signals to and from the toolcarriage may be located near or on the backbone 318 (e.g., looselytacked onto the backbone 318 with sufficient slack to accommodatemovement of the tool carriage).

As best shown in FIG. 2A, the base may further include a housing 219,which may house or cover at least some of the above-describedcomponents, such as the backbone 318, motor module 362, and proximalmounting block 391. The housing may define, for example, an internalvolume that accommodates the various components of the base describedabove. Additionally, there may be enough clearance between thecomponents and the housing 219 to facilitate sufficient airflow forthermal management purposes. The housing 219 may be made of plastic orother suitable material, and may be injection molded, machined, orformed in any suitable manner to include a recessed internal volume.Furthermore, in some variations, as shown best in FIG. 2C, the housingmay include one or more features (e.g., curved or semi-circular cutout217) to improve physical clearance with the robotic arm to which thetool driver is attached, thereby increasing the available range ofmotion of the robotic surgical system.

As shown in FIG. 3A, the tool driver 310 may include an arm adapter 312configured to couple the tool driver to a robotic arm. The arm adapter312 may, for example, be located on distal mounting block 393 andinclude a hole configured to receive and couple to an output shaft of anactuator assembly disposed at a distal end of a robotic arm or othermanipulator, such that when the actuator assembly on the robotic armprovides a rotational output, the tool driver 310 rotatescorrespondingly relative to the robotic arm. Alternatively, the armadapter 312 may include an actuator assembly with an output shaft thatcouples to a distal end of a robotic arm, such that when the actuatorassembly on the tool driver provides a rotational output, the tooldriver 310 rotates relative to the robotic arm.

Generally, the tool driver 310 may further include a cannula adapter 314configured to receive a cannula to permit the tool driver to couple tothe cannula, such that the cannula and a shaft of the tool are aligned.The cannula adapter 314 allows for coupling of the tool driver and thecannula. In some variations, the cannula adapter 314 may require adeliberate user action to facilitate decoupling of the tool driver andthe cannula (e.g., pushing a button, squeezing a latch release, etc.) tohelp avoid accidental or unintentional decoupling of the tool driver andthe cannula. For example, various clamps or other retention devices mayenable engagement and retention of the cannula to the cannula adapter.Exemplary variations of cannula adapters for coupling the tool driver tothe cannula are described in U.S. Provisional Patent Application No.62/548,292 titled “CANNULA ATTACHMENT DEVICES AND METHODS FOR A SURGICALROBOTIC SYSTEM” and filed Aug. 21, 2017, which is incorporated herein inits entirety by this reference.

Tool Carriage

Generally, the tool carriage is configured to provide various degrees offreedom of movement for the surgical tool coupled to the tool carriage.As described above, longitudinal movement of the tool carriage along thebase provides a translational degree of freedom for the surgical toolalong a tool axis. Additionally, the tool carriage may be configured toprovide a rotational degree of freedom for rotation of the surgical toolaround a tool axis, as well as various degrees of freedom for actuationor articulation of an end effector of the surgical tool (e.g., graspingor cutting). For example, the tool carriage may include one or moremotor drives (e.g., linear axis drive or rotary axis drive) whoseoutputs may be coupled to the input driving mechanisms of a surgicaltool, where a first motor drive may actuate a first degree of freedom(e.g., manipulate one jaw of a clamp end effector), a second motor drivemay actuate a second degree of freedom (e.g., manipulate a second jaw ofthe clam end effector), and similar for additional motor drives in thetool carriage. Additionally, at least one motor drive may actuaterotation of the tool shaft in a first direction (e.g., clockwise) andanother motor drive may actuate rotation of the tool shaft in a seconddirection opposite the first (e.g., counter-clockwise) in antagonisticfashion. Alternatively, at least one motor drive may actuate rotation ofthe tool shaft in two directions (e.g., both clockwise andcounter-clockwise). Such actuation of the tool may involve, for example,a cable-driven mechanism or set of mechanisms in the tool that arecoupled to the output of the motor drives in the tool carriage.Exemplary variations of the tool carriage are described below.

Combined Axis Drive Carriage Variation

In one variation, a tool carriage may include a combination of at leastone linear axis drive and at least one rotary axis drive. For example,the tool carriage may include four linear axis drives configured toactuate a set of one or more articulated movements of the end effectorof the tool (e.g., by a pusher that extends and retracts along alongitudinal axis of the pusher), and two rotary axis drives configuredto rotate the tool shaft around a tool axis. However, other suitablenumbers of linear axis drives and rotary axis drives may be included inany suitable combination in the tool carriage.

As shown in FIG. 4A, a tool carriage 400 may include housing 412 whichencloses the linear axis drives and/or rotary axis drives. A secondhousing (not shown) may further enclose the housing 412 and associatedcarriage electronics (e.g., PCB 480). The housing 412 may be configuredto mount to the base or stage of the tool driver via fastenersinsertable in mounting holes 420. For instance, the mounting holes 420may be on both a left side and a right side of the carriage 400, and maybe threaded so as to receive threaded screws or other fasteners thatcouple the housing 412 to a bracket on the base (e.g., bracket 322 onbase 310, as shown in FIGS. 3A and 3B) or other suitable structure onthe base. Additionally, the carriage 400 may be configured to receive asurgical tool. A sterile adapter 490 may generally be provided to createand maintain a sterile barrier between the non-sterile drive axes of thecarriage 400 and a sterile surgical tool. Exemplary variations ofsterile adapters are described in U.S. Provisional Patent ApplicationNo. 62/526,871 titled “STERILE ADAPTER FOR A LINEARLY-ACTUATINGINSTRUMENT DRIVER” and filed Jun. 29, 2017, which is incorporated hereinin its entirety by this reference.

As shown in FIG. 4B (depicting the tool carriage 400 without the sterileadapter 490 and without top plate 410 of the housing 412), the carriage400 may be bilaterally symmetrical. For example, a left side 400 a ofthe carriage 400 may include a first linear axis drive 450 a (shown in aretracted state), a second linear axis drive 450 b (shown in an extendedstate), and a first rotary axis drive 430 a. Similarly, a right side 400b of the carriage 400 may include a third linear axis drive 450 c, afourth linear axis drive 450 d, and a second rotary axis drive 430 b.The first side 400 a and second side 400 b of the carriage 400 may, forexample, be mirrored halves of the carriage that are coupled together.Additionally, as shown in FIG. 4C, a left housing side 412 a and a righthousing side 412 b in the carriage 400 may be coupled together with ajoining plate 402 attached at both ends by fasteners 404 to the left andright housing sides 412 a and 412 b. Alternatively, the left and righthousing sides 412 a and 412 b may be coupled together with interlockinggeometry (e.g., tabs and slots), epoxy, or in any suitable manner.

An example of a left carriage side 400 a is shown in FIG. 4D. Linearaxis drive 450 a is generally actuated by motor assembly 452 a, andlinear axis drive 450 b is generally actuated by motor assembly 452 b(e.g., motor assemblies 452 a and 452 b may be similar to that describedwith respect to FIG. 5A below). Rotary axis drive 430 a is generallyactuated by motor assembly 454 a (e.g., described with respect to FIGS.8A-8C below). A right carriage side 400 b may be a similar, mirroredversion of the left carriage side 400 a (e.g., to simplify manufacturingfor using common parts shared between the left and right carriagesides).

As shown in FIG. 4E (depicting the tool carriage 400 without the sterileadapter 490), in some variations, the tool carriage may include a topplate 410 that couples to the housing 412 via fasteners (e.g., screws)and is disposed between the housing 412 and the sterile adapter 490. Thetop plate 410 may include one or more openings to permit passage of theoutput of the linear axis drives (e.g., 450 a, 450 b, 450 c, 450 d)and/or the output of the rotary axis drives (e.g., 430 a, 430 b).Furthermore, the top plate 410 may include a single rigid or semi-rigidplate that is configured to help join together the mirrored right andleft carriage sides of the tool carriage 400.

Linear Axis Drive

As shown in FIG. 5A, an exemplary linear axis drive 500 includes a motorassembly 502, a ball screw assembly 504 driven by the motor assembly,and a pusher element 522 coupled to at least a portion of the ball screwassembly 504 and configured to move linearly. Multiple instances of thelinear axis drive 500 may be included in the tool carriage, so as toprovide actuation for multiple degrees of freedom of the tool.

In the linear axis drive 500, the motor assembly may include a motor 552(e.g., a brushless DC motor or other suitable motor), a rotary encoder554 configured to measure rotational or angular position of the motorshaft of the motor 552, and/or a gear transmission 556 (e.g., planetarygear train) configured to increase torque output of the motor assembly.The encoder 554 and/or the gear transmission 556 may be modularcomponents of the motor assembly, such as with encoder 554 located at aproximal end of the motor 552 and the gear transmission 556 coupled toan output shaft of the motor 552. In other variations, the encoder 554and/or the gear transmission 556 may be incorporated in the motor 552(e.g., gear transmission 556 located in a rotor of the motor 552, asfurther described below with respect to FIGS. 15A and 15B).

The motor drive output of the motor assembly may be coupled to the inputof the ball screw assembly via a series of gears, such that rotation ofthe motor assembly induces rotation of the ball screw in the ball screwassembly. For example, as shown best in FIGS. 5B and 5C, the series ofgears may include a motor drive gear 558, such as a spur gear or othersuitable gear, mounted to the output of the motor assembly (e.g., outputshaft of gear transmission 556), an idler gear 459 mounted on bearings557 and engaged with the motor drive gear 558, and a ball screw gear 560engaged with the idler gear 559 and mounted to the input of ball screw562. The number of teeth on the motor drive gear 558, the idler gear559, and the ball screw gear 560 may be selected to optimize the designof the absolute multi-turn encoder (further described below) formeasuring linear position of the ball nut or other linearly travelingelements. For example, in one exemplary variation depicted in FIG. 5C,the motor drive gear may have thirty-two teeth and the ball screw gear560 may have thirty-nine teeth. Additionally or alternatively, therelative numbers of teeth on at least the motor drive gear 558 and theball screw gear 560 may be selected to provide additional suitabletorque increase. Additionally, an even number (two, four, etc.) of idlergears may be included to adjust the directionality of the ball screw fordesired travel. The series of gears may be made of any suitablematerial, including but not limited to metallic materials such as steel(e.g., 304 stainless steel) and plastic materials such aspolyoxymethylene (e.g., DELRIN) which has high stiffness and lowfriction.

The ball screw assembly converts the rotational output of the motorassembly into linear motion. As shown in FIG. 5A, the ball screwassembly includes a ball screw 566, and an axially-movable ball nutguide 568 threadingly mounted on and engaged with the ball screw 566.The axially-movable ball nut guide 568 may include, for example, a ballnut 567 engaged with the ball screw 566. The ball nut 567 may be aseparate piece coupled to the rest of the guide 568 (e.g., with epoxy,interference fit, etc.) or may be integrally formed with the guide 568(e.g., the guide 568 may include an internally threaded hole to engagewith the ball screw 566). The ball screw 566 may be mounted at aproximal end to a ball screw mount portion 565 in the carriage housing,such as with an inner race clamp nut 561 and outer race clamp 562.Rotation of the ball screw 566 around a longitudinal axis of the ballscrew 566 may be facilitated with one or more bearings 564. As describedabove, rotational output of the motor assembly induces rotation of theball screw 566 in the ball screw assembly via a series of gears (motordrive gear 558, ball screw gear 560, etc.). When the ball screw 566rotates, the ball nut 567 travels linearly along the ball screw 566.Ball nut guide 568, which is coupled to the ball nut 567, also travelslinearly with the ball nut 547 along a ball nut guide rail 569 (e.g.,linear bearing), which may, for example, help maintain linear alignmentof the ball nut 567 and ball nut guide 568. In other variations, thelinear axis drive may include a belt drive, a pulley-and-cable system,or the like in order to couple the rotational output of the motorassembly to the ball screw 566. Furthermore, in some variations, aleadscrew may be included in lieu of a ball screw.

As shown in FIG. 5A, a pusher element 522 is configured to travellinearly in correspondence with the ball nut 567 and ball nut guide 568.The pusher element 522 may be, for example, a cap or sleeve-like elementwith an internal volume or other space that receives a distal portion ofthe ball screw 566. When the ball nut 567 and ball nut guide 568 are ina proximal position (e.g., as shown in FIG. 5A), the pusher element 522may be in a retracted state. In contrast, when the ball nut 567 and ballnut guide 568 are in a distal position (e.g., similar to ball nut guides468 a and 468 b traveling on ball screws 466 a and 466 b, respectively,as shown in FIG. 4D), the pusher element may be in an extended state.Generally, rotation of the motor 552 in a first direction results inlinear translation of the pusher element 522 (via the series of gearsand the ball screw assembly) in one direction along the ball screw 566(e.g., in a proximal direction), while rotation of the motor 552 in asecond, opposite direction results in linear translation of the pusherelement 522 in an opposite direction along the ball screw 566 (e.g., ina distal direction).

Rotary Axis Drive

As shown in FIGS. 8A-8C, an exemplary rotary axis drive 800 includes amotor assembly and an output assembly 820 rotationally coupled to anoutput of the motor assembly. Multiple instances of the rotary axisdrive 800 may be included in the tool carriage, so as to provideantagonistic rotational actuation of a surgical tool around a tool axis,and/or actuation for any other degree of freedom of the tool (e.g.,articulation of an end effector of the tool).

Similar to the linear axis drive 500 shown in FIG. 5A, the motorassembly in the rotary axis drive 800 may include a motor 810 (e.g., abrushless DC motor or other suitable motor), a rotary encoder 812configured to measure rotational or angular position of the motor shaftof the motor 810, and/or a gear transmission 814 (e.g., planetary geartrain, harmonic drive, etc.) configured to increase torque output of themotor assembly. The encoder 812 and/or the gear transmission 814 may bemodular components of the motor assembly, such as with encoder 812located at a proximal end of the motor 810 and the gear transmission 814coupled to an output shaft of the motor 810. In other variations, theencoder 812 and/or the gear transmission 814 may be incorporated in themotor 810 (e.g., gear transmission 814 located in a rotor of the motor810, as further described below with respect to FIGS. 15A and 15B.

As shown in FIGS. 8B and 8C, the output assembly 820 may include arotary shaft 821 that is coupled to an output shaft 816 (e.g., outputshaft of a planetary gear train, or other output of a gear transmission814) of the motor assembly, such as with one or more set screws 824. Theoutput assembly 820 may further include a rotary axis drive outputcoupler 830, including a rotary axis drive output head 832 and a rotaryaxis drive output shaft 834, where the output coupler 830 is coupled tothe rotary shaft 821 and configured to move in both rotational andtranslational (axial) manners. For rotational motion, the output head832 of the output coupler 830 may be coupled to the rotary shaft 821 viaa drive pin 836 operating similar to a mechanical key, such that theoutput head 832 rotates with the rotary shaft 821 whenever the motorassembly provides rotational actuation to the rotary shaft 821. Fortranslational motion, the output shaft 834 may be coupled to a spring826 for biased linear movement towards an extended, tool-engagingposition. For example, a pre-loaded compression spring 826 may bedisposed in a lumen of the rotary shaft 821 and coupled to the rotaryaxis drive output shaft 834 with a retaining ring 828 or other suitablemechanism. The spring 826 may be configured to urge the rotary driveoutput coupler outwards to an extended position, and one or more linearbearings 840 (e.g., bushing or sleeve bearing) may be provided to reducefriction of this translational movement. The extended position of therotary drive output coupler may, for example, be conducive for engagingwith the input of a surgical tool and/or sterile barrier located betweenthe tool drive rand the tool, etc.

Carriage Sensors

In addition to or alternative to the various sensors briefly describedabove, any one or more linear axis drives rotary axis drives in the toolcarriage may include other suitable sensor assemblies for measuringposition, force (e.g., compression or tension) or other metrics. Suchmetrics may be used, for example, for tracking position and orientationof the various degrees of freedom of an end effector on the surgicaltool, and/or as force feedback in control algorithms.

Absolute Multi-Turn Encoder

In some variations, the linear axis drive may further include one ormore sensors configured to determine the axial (linear) position of thelinearly traveling elements on the linear axis drive (e.g., ball nut567, ball nut guide 568, and/or pusher element 522). Some variations ofa tool driver may include, for example, a position sensor for measuringaxial position of the guide based on relative rotational positions ofgears, or any suitable position sensor (e.g., proximity sensors,tracking markers, etc.).

For example, as shown in FIG. 5A, the linear axis drive 500 may includean absolute multi-turn encoder 570 leveraging the Vernier principle. Theabsolute multi-turn encoder may determine the relative rotationalpositions (angular orientation) of at least two gears in the linear axisdrive, which may be mapped to an absolute linear position of thelinearly traveling elements on the linear axis drive. Alternatively, oneor more suitable encoders or other sensors may be used to detect therotational position of the output of the motor 552 or motor assembly,and/or rotational position of the motor drive gear 558, idler gear 559,and/or ball screw gear 560, which may be transformed into a linearposition sensor. For example, an encoder may measure the rotationalposition of the ball screw gear 560 alone, and a processor may convertthe rotational position to a linear position of one or more of thelinearly traveling elements. In some variations, such an encoder mayneed to be zeroed (e.g., during calibration or setup) to set a referencepoint relative to which dynamic linear position is measured.Advantageously, in the applications described herein, as well as inother suitable applications in which a linearly traveling element (e.g.,ball nut on a ball screw or leadscrew, etc.) is driven by a rotationalelement, an absolute multi-turn encoder may be used to measure linearposition of the linearly traveling element without requiring a sensordirectly on the linearly traveling element. Accordingly, electronics forthe absolute multi-turn encoder may be relatively simplified andcompact, such as contained on a PCB mounted next to the rotationalelement, in contrast to typical sensor electronics that require physicalaccommodations for communicating with a linearly traveling sensor (e.g.,with flex cables between a PCB and the linearly traveling sensor, etc.).

Generally, in the absolute multi-turn encoder, the respective rotationalpositions of at least two gears may be measured and used in combinationto determine the number of total and partial turns that one of the gearshas rotated, which may be used to determine a measure of absoluteposition relative to a zero position. The principle of operation of theabsolute multi-turn encoder for measuring absolute linear position isillustrated in the schematic of FIGS. 6B-6D, which depict a firstmeasured gear 610, an idler gear 620 engaged with the first measuredgear 610, and a second measured gear 630 engaged with the idler gear 620and having a different number of teeth than the first measured gear 610.Like the motor drive gear 558 shown in FIG. 5C, the first measured gear610 may be coupled to an output of a motor assembly. Additionally, likethe ball screw gear 560 shown in FIG. 5C, the second measured gear 630may be coupled to a ball screw, such as ball screw 640 with linearlytraveling ball nut 650. Additionally, like the idler gear 559 shown inFIG. 5C, the idler gear 620 may be engaged with the first measured gear610 on one side and with the second measured gear 620 on another side.However, the idler gear 620 may be omitted in some variations. Each gearmay have any rotational position (angular orientation), such as any ofthose shown in FIG. 6A, including a position A, a position B which isrotated 90 degrees clockwise from position A, position C which isrotated 90 degrees clockwise from position B, or position D which isrotated 90 degrees clockwise from position C, or any rotational positionbetween any of these positions. FIG. 6B depicts the first measured gear610, the idler gear 620, and the second measured gear 630 in position A,which may correspond to a first location of the ball nut 650 on the ballscrew 640. The gear orientations in FIG. 6B may, for example, beconsidered a “zero” absolute position. In FIG. 6C, the first measuredgear 610 has rotated clockwise to position B, causing the idler gear 620to rotate counter-clockwise to position D. The second measured gear 620has rotated clockwise to a position intermediate between positions A andB (a smaller degree of rotation due to the second measured gear 620having more teeth than the idler gear 620), resulting in the ball nut650 traveling to a second location (e.g., distal to the first location)of the ball nut 650 on the ball screw 640. Continued rotation of thefirst measured gear 610, idler gear 620, and second measured gear 630may further drive the ball nut 650 to more distal locations on the ballscrew 640, until the configuration shown in FIG. 6D. In FIG. 6D, thefirst measured gear 610 and the idler gear 620 have returned to positionA, while the second measured gear 630 is in position C, resulting in theball nut 650 traveling to a third location (e.g., distal to the secondlocation) of the ball nut 650 on the ball screw 640. Comparing the gearorientations in FIGS. 6B and 6D, although in both FIGS. 6B and 6D thefirst measured gear 610 and the idler gear 620 are in position A, thesecond measured gear 630 is in position A in FIG. 6A and in position Din FIG. 6D. The different position of the second measured gear 630 inFIG. 6D indicates that the first measured gear 610 has rotated (here,rotated a full single turn) relative to FIG. 6B, which could not bedetermined without determining the position of second measured gear 630.Accordingly, the combined set of rotational positions of the firstmeasured gear 610 and the second measured gear 630 in FIG. 6B isdistinct from the combined set in FIG. 6D, which when measured enablesdetermination of distinct linear positions of the ball nut 650 on theball screw 640.

Furthermore, in the absolute multi-turn encoder, the total number ofmeasurable turns (and/or measurable range of linear movement, if pairedwith a ball screw or leadscrew) is based at least partially on the gearratio between the measured gears. The measurement of the rotationalposition of the first measured gear 610 and the second measured gear 630(or alternatively or additionally the idler gear 620) may be mapped toan absolute linear position of the ball nut 650 within a certain rangethat is limited by the possible amount of “wrap,” or continued rotationof the gears, before the gears return to the zero absolute position. Inother words, if the smaller measured gear has “m” teeth and the largermeasured gear as “n” teeth (where m<n), then the encoder candiscriminate rotational positions of the gears throughout “n” turns ofthe smaller gear. Different gear ratios (i.e., the numbers of teeth ofthe measured gears) may be selected at least in part to obtain asuitable measurable range of absolute position. Furthermore, the idlergear 620 may be omitted, or replaced by a split idler gear (e.g.,described with respect to FIG. 5D) to increase the absolute distance orposition that is measurable by the absolute multi-turn encoder (byincreasing the number of possible turns before the series of gearscollectively return to the zero absolute positions) without requiring anincrease in the size of the measured gears 610 and 630.

Thus, the absolute multi-turn encoder may be a compact, space- andpart-efficient way to enable detection of an absolute rotation angle ofa shaft and/or gears with high precision (high resolution). In somevariations, the encoder may detect absolute rotational position withinabout 0.1 degree precision, within about 0.05 degree precision, orwithin about 0.03 degree precision. The multi-turn encoder may be usedalone to determine rotational position of shafts. Additionally, whenused in combination with a ball screw or leadscrew (e.g., at shown inFIG. 5A), the geometric relationship between the gears and the ballscrew or leadscrew may enable measurement of the absolute linearposition of the ball screw or leadscrew with similarly high precision(e.g., a resolution or precision within less than 50 μm, less than 45μm, less than 40 μm, less than 30 μm, or 25 μm or less, etc.).Furthermore, the encoder may enable measurement of an absolute positionwithin a range that is larger than that of typical encoders (e.g., thatare based on measurement of a single rotational position).Advantageously, the absolute multi-turn encoder may not require zeroingor recalibration in order to determine rotational position.

The absolute multi-turn encoder may be convenient to implement insystems that already include a gear train, but may still be incorporatedin systems with no gears or an insufficient number of gears, byintroducing “dummy” gears (e.g., gears not driving anything, and arerotationally driven simply for purposes of providing information for themulti-turn encoder). For example, to measure rotational position of anoutput shaft in a system not requiring a gear train, a set of at leasttwo dummy gears may be introduced, with one dummy gear attached to theoutput shaft. As another example, if a higher number of turns (andlarger measurable range of position) is desired without increasing thenumber of teeth on the gears in the gear train, a fractional gear ratiomay be introduced by including a dummy split gear (e.g., gear 368 asshown in FIG. 3D).

In an exemplary implementation, as shown in FIG. 5A, the magneticencoder 570 may be an absolute multi-turn encoder. As best shown in FIG.5D, the magnetic encoder 570 may be configured to detect the relativeangular orientation of at least two gears in the linear axis drive, suchas with a sensor 570 a detecting angular orientation of the motor drivegear 558 and a sensor 570 b detecting angular orientation of the ballscrew gear 560 (e.g., via magnets and Hall effect sensors, or othersuitable rotary encoders for each measured gear). A relationship betweenthe set of angular orientations of the gears 558 and 560 and the linearposition of the linearly traveling elements (e.g., ball nut 567, ballnut guide 568, and/or pusher element 522) may be determined, based onthe number of teeth on the gears 558 and 560 and on the threadcharacteristics of the ball screw 566 (e.g., thread angle, pitch).Accordingly, measurement of the angular orientation of the gears 558 and560 (or additionally or alternatively idler gear 559) may be transformedor mapped into information regarding the absolute linear position of thelinearly traveling elements, at least within a certain measurable range.The measurable range of absolute linear position may be based on, forexample, the relative number of teeth of the measured gears and/or pitchof the gears. For example, as depicted in FIG. 5C, the motor drive gear558 may have thirty-two teeth and the ball screw gear 560 may havethirty-nine teeth. This exemplary ratio (32:39) results in the ballscrew gear 560 “wrapping” to a reference zero position every thirty-tworevolutions of the ball screw gear 560, which limits the measurableabsolute distance of the linearly traveling elements. In an exemplaryvariation in which the ball screw gear 560 has a pitch of about 1 mm,the measurable range of absolute linear position of about 32 mm, withe.g., about 25 μm of resolution.

In some variations, as shown in FIG. 5D, the series of gears for theabsolute multi-turn encoder may include split idler gears including afirst idler gear 559 a and a second idler gear 559 b, where the firstidler gear 559 a is engaged with the motor drive gear 558, the secondidler gear 559 b is rotating with the first idler gear 559 a about thesame axis, and the second idler gear 559 b is engaged with the ballscrew gear 560. The first idler gear 559 a and the second idler gear 559b may have different numbers of teeth (e.g., the second idler gear 559 bmay have fewer teeth than the first idler gear 559 a, or may have moreteeth than the first idler gear 559 a) to further facilitate aparticular gear ratio. Additionally or alternatively, the first andsecond idler gears 559 a and 559 b may further increase the absolutedistance or position that is measurable by the absolute multi-turnencoder (by increasing the number of possible turns before the series ofgears collectively return to the zero absolute positions) withoutrequiring an increase in the size of the motor drive gear 558 and/orball screw gear 560.

In some variations, the motor drive gear 558 may have between 10 and 25teeth, or between 15 and 20 teeth, etc., the first and/or second idlergears 559 a and 559 b may have between 25 and 45 teeth, or between 30and 40 teeth, etc., and the ball screw gear 560 may include between 15and 45 teeth, between 25 and 35 teeth, etc. Additionally, in somevariations, the series of gears for the absolute multi-turn encoder mayenable between 100 and 200 turns, between 110 and 175 turns, or between120 and 150 turns, etc. before returning to the zero absolute positions.Other suitable combinations of gears may facilitate a suitable gearratio and a suitable measurable number of turns (correlating tomeasurable absolute distance). For example, the motor drive gear 558 mayinclude seventeen teeth, the first idler gear 559 a may includethirty-six teeth, the second idler gear 559 b may include thirty-twoteeth, and the ball screw gear 560 may include twenty-seven teeth, whichprovides a gear ratio of about 1.79 and over 135 turns' worth ofmeasurable absolute distance. As another example, the motor drive gear558 may include seventeen teeth, the first idler gear 559 a may includethirty-six teeth, the second idler gear 559 b may include thirty-twoteeth, and the ball screw gear 560 may include twenty-nine teeth, whichprovides a gear ratio of about 1.92 and over 135 turns' worth ofmeasurable absolute distance. As yet another example, the motor drivegear 558 may include seventeen teeth, the first idler gear 559 a mayinclude thirty-six teeth, the second idler gear 559 b may includethirty-two teeth, and the ball screw gear 560 may include thirty-oneteeth, which provides a gear ratio of about 2.05 and 136 turns' worth ofmeasurable absolute distance.

Furthermore, the absolute multi-turn encoder may be implemented in otherparts of the tool driver. For example, as discussed above, the absolutemulti-turn encoder may be used to measure absolute linear position ofthe carriage on the stage (e.g., using the gear train shown in FIG. 3D).The absolute multi-turn encoder may be implemented in other variationsof the tool driver (e.g., other variations of the carriage) or otherapplications in which it is desirable to measure rotational positionand/or linear position.

Compact Load Cell

In some variations, the linear axis drive may include one or more forcesensors configured to determine the axial load placed on the linear axisdrive (e.g., ball screw), which may be used as feedback in controllingthe linear axis drive in the tool drive. For example, as shown in FIG.5A, a load cell 570 may be disposed on the ball screw distal to the ballscrew nut 567 and proximal to the pusher element 522, such that the loadcell 570 is configured to measure axial loads (push and/or pull forces)on the ball screw. The space distal to the ball screw nut is verylimited and it is difficult to place a conventional load cell in thespace between the ball screw nut 567 and the pusher element 522. Thus,in some variations, the load cell 570 may include a compact, hollow loadcell such as the capacitive compact load cell 700 shown in FIGS. 7A-7F.

The capacitive compact load cell 700 described herein have a number ofadditional advantages. For example, in the applications described hereinand in other applications in which axial load is to be measured, thecapacitive compact load cell 700 may provide a data signal that is morerobust against noise (e.g., due to electromagnetic interference,temperature variation and/or humidity variation, etc.) than conventionalstrain gauge-based load cells. For example, conventional strain gaugeload cells typically provide raw signal data with low amplitude (i.e.,low voltage ranges) which, for practical purposes, must be processedwith analog and/or digital amplifiers to provide useful information.Furthermore, since the signal-to-noise ratio is low, noise in the rawsensor data is also amplified, such that further signal processing withfilters and other complicated circuitry or digital processing methodsmust also be performed on the signal to isolate the force data. Incontrast, the capacitive compact load cell 700 provides raw capacitancesignal that has a relatively high amplitude (e.g., higher voltageranges), or a high signal-to-noise ratio, thereby making the capacitivecompact load cell 700 more immune or resilient against noise.Additionally, the high signal-to-noise ratio facilitatesstraightforward, simple calibration of the signal output. Furthermore,as described below, the load cell 700 includes a small number of partsthat are straightforward and easy to manufacture and assemble.

Generally, in one variation as shown in FIGS. 7A-7E, a compact load cell700 includes a housing 710 with a recess 718, a first conductive plate730 disposed in the recess 718, and a second conductive plate 740disposed in the recess 718 and facing the first conductive plate 730. Asshown in FIG. 7B, the housing 710 includes a central region 712, anouter region 714, and a spring structure 716 connecting the centralregion 712 and the outer region 714 such that the central and outerregions of the housing 710 may flex relative to one another. The centralregion 712 may be configured to receive an axial load directed along acenterline of the load cell. For example, as shown in FIG. 7B, thecentral region 712 may include an opening 713. The opening 713 may beinternally threaded to receive and engage with a ball screw 780 (orleadscrew), as shown in FIG. 7C. Accordingly, in the example shown inFIG. 7C, when the ball screw 780 receives an axial load (i.e., aproximally-directed or distally-directed) while threadingly engaged withthe central housing region 712 via opening 713, the axial load causesdeflection of the spring 716. In other examples, the central region 712may include a ball seat (or groove or other surface engagement)configured to receive a load-receiving member.

The housing 710 may, in some variations, be made from a single unitarypart. It may be manufactured through any suitable machining process(e.g., with a mill, lathe, etc.), casting, or other suitablemanufacturing process to include the desired compact shape, geometry ofthe central region 712 and outer region 714, geometry of the springstructure 716, thread characteristics of the opening 713, etc.Alternatively, the housing may include multiple parts (e.g., separatecentral region 712 and outer region 714 sections) that are assembled andjoined together to form the housing. The housing may be made of asuitable material that provides electromagnetic shielding for theconductive plates and associated electronics disposed within the housing710, such as aluminum or steel, to reduce electromagnetic noise thatmight confound sensor readings.

As shown in FIG. 7B, the first conductive plate 730 and the secondconductive plate 740 may be disposed within the recess 718 of thehousing 710 and arranged to face each other. In some variations, thefirst conductive plate 730 may include an opening 732, and the secondconductive plate 740 may include an opening 742, where the openings 732and 742 are aligned with the opening 713 such that the ball screw 780may pass through the housing 710 (by passing through threaded opening713), through the first conductive plate 730 (by passing through theopening 732), and through the second conductive plate 740 (by passingthrough the opening 742). As such, the openings 732 and 742 in the firstand second conductive plates may be of sufficiently larger diameter thanthe opening 713 in the central region 712 of the housing, to enable theball screw 780 to pass with clearance.

One of the conductive plates (e.g., the second conductive plate 740) maybe the “active” or “sensor” conductive plate, and include electronics750 for measuring the capacitance between the first and secondconductive plates. In some variations, the electronics 750 may includemultiple active signal channels (e.g., two, three, four, five, six,etc.) for redundancy purposes. For example, if one or more of the activesignal channels returns an error (no signal, signal outside apredetermined acceptable signal range, etc.), then force data from atleast one other functioning active signal channel may be used instead.Furthermore, co-location of the electronics 750 on the sensor (on one ormore conductive plates) may be advantageous. For example, such aco-located arrangement of the electronics 750 may enable the housing 710to substantially surround the electronics 750 and provideelectromagnetic shielding against noise. As another example, theelectronics 750 located on the sensor may reduce or eliminate the needfor wiring to communicate signals between the sensor and an additionalPCB located external to the housing 710.

The first conductive plate 730 may be coupled to the central region 712of the housing 710 (e.g., by epoxy or other fastener at locations 734).The second conductive plate 740 may be coupled to the outer region 714of the housing 710 (e.g., by epoxy or other fastener at locations 744)such that the first and second conductive plates 730 and 740 aresubstantially parallel to one another. As another example, as shown inthe variation of the load cell 700′ depicted in FIG. 7I, at least one ofthe conductive plates (e.g., second conductive plate 740) may includeone or more radially extending extensions or tabs 747 that areconfigured to engage cutouts 715 in the outer region 714 of the housing.Such tabs 747 may help restrain rotational motion relative to thehousing 710 and/or help couple, for example, the second conductive plate740 to the housing 710.

In some variations, such as load cell 700′ as shown in FIGS. 7H and 7I,the load cell 700′ may be similar to load cell 700 described withreference to FIGS. 7A-7E, except as described below. Load cell 700′ mayinclude a third conductive plate or reference conductive plate 790 whichmay serve as a reference pad for temperature and/or humidity calibration(e.g., to compensate for temperature, humidity, and other environmentalvariations). The reference conductive plate 790 may be configured to beadjacent to a second face of the second conductive plate 740, where thesecond face is directed away from the first conductive plate 730, suchthat as shown in FIG. 7H, the second conductive plate 740 is disposedbetween the first conductive plate 730 and the reference conductiveplate 790. The reference conductive plate 790 may be mounted, forexample, to the outer region 714 of the housing via pins engagingperipherally-arranged mounting holes 794. Additionally, the electronics750 may include a reference channel (e.g., corresponding to capacitancemeasured between a reference conductive plate 790 and the active secondconductive plate 740) that communicates a signal that includesinformation that may be used for calibration against temperature and/orhumidity variations.

In some variations, the reference conductive plate 790 may be smallerthan the first conductive plate 730 and/or the second conductive plate740, which may, for example, permit clearance for the electronics 750when the first conductive plate 730, the second conductive plate 740,and the reference conductive plate 790 are stacked upon one another inthe housing, thereby reducing the need to increase height of the loadcell to accommodate the reference conductive plate 790. For example, insome variations in which the first and/or second conductive plates aregenerally circular in shape, the reference conductive plate 790 may begenerally in the shape of a segment of a circle (e.g., generallysemi-circular, or any suitable portion of a circle) or an annularsegment (as shown in FIG. 7J). Furthermore, the reference conductiveplate 790 may have a shape configured to provide an axial passagethrough a central region (e.g., a clearance cutout 792) that isconfigured to be aligned with openings 732 and 742 in the first andsecond conductive plates, respectively. The conductive plates may besensitive to gap size variations between the first and second conductiveplates. Accordingly, the load cell may enable detection of axial loadsbased on change in capacitance resulting from the gap size variations.For example, if an external force acts axially to deform the housingproportional to the external force, or to cause the central region 712to move relative to the outer region 714 of the housing (e.g., axialloads on the ball screw 780 which cause the central region 712 to flexrelative to the outer region 714), then the axial displacement of thefirst and second conductive plates, or reduction/expansion of gapdistance, is measureable by detecting the resulting change incapacitance from the first and second conductive plates. Thus, thespace-efficient conductive components within the hollow housing 710enable the load cell 700 to be compact and suitable for tight or limitedspaces in which axial load measurement may be desired. For example, insome variations, the housing is between 10 mm and 15 mm in diameter(e.g., 12 mm in diameter) and between 2 mm and 5 mm tall (e.g., 3.5 mm),though the housing may include any suitable dimensions.

As shown in FIG. 7F, the compact load cell 700 may be integrated into alinear axis tool drive shown in FIG. 5A, distal to the ball nut guide760 in a low-space environment. For example, the load cell may bedisposed on the ball screw between the ball nut guide and the distal endof the threaded shaft (e.g., the pusher element), such that a firstconductive plate is referenced (e.g., fixed) relative to the ball nutguide and a second conductive plate is referenced (e.g., fixed) relativeto the threaded shaft.

For example, as shown in FIGS. 7J and 7K, the housing 710 may include atleast one housing extension 724 extending radially outward from theouter region 714 of the housing, and the conductive plates (e.g., firstconductive plate 730, second conductive plate 740, and referenceconductive plate 790) of the housing 710 may be enclosed in the recessof the housing by a base plate 720. The base plate 720 and housing 710may be mounted to the ball screw nut guide 760 with fasteners (e.g.,screws) 722 securing the housing extensions 724 and the base plate 720to mating features on the ball screw nut guide 760. Accordingly, axialloads on the ball screw 770 (e.g., via pusher 770) cause deflectionbetween the central region 712 and outer region 714 in the housing ofthe compact load cell 700, and therefore further causes a correspondingdetectable change in capacitance between the first conductive plate 730(coupled to the central region 712) and the second conductive plate 740(coupled to the outer region 714). As pictured in FIG. 7F, the housing710 may include a plurality of housing extensions 724 distributedgenerally around a circumferential perimeter of the load cell 700, butin other variations, the housing 710 may include a housing extension 724in the shape of an annular ring or flange, or any other suitablestructure for mounting the housing 710 to the ball nut guide 760.

Additionally, in some variations, the central region 712 of the housingmay include a central structure 711. The central structure 711 mayinclude a lumen as shown in FIG. 7K (e.g., to allow passage of a ballscrew 780 as shown in FIG. 7C, etc.), but may alternatively besubstantially solid (e.g., in variations in which a central passagethrough the load cell is not needed, such as if the central region 712includes a ball seat for receiving axial load). As shown in FIG. 7K, thecentral structure 711 may extend axially through at least most of therecess of the housing through the conductive plates (e.g., 730, 740, and790 if included). As such, the central structure 711 may help provide anenvironmental seal for the housing and its conductive plates and othercomponents, such as to protect against dirt, grease, and/or otherdebris. Furthermore, the central structure 711 prevents an excessivecompressive force from overloading the load cell. A clearance gap 717between the central structure 711 and the base plate 720 generallypermits the central region 712 to move axially relative to the outerregion 714 of the housing within a predetermined range of motion(correlated to the measurable range of gap distance between the firstconductive plate 730 and the second conductive plate 740). As thecentral region 712 moves axially relative to the outer region 714, thedistance of the gap 717 varies. However, physical interference betweenthe central structure 711 and the base plate 720 occurs when the centralstructure 711 moves toward the base plate 720 until it abuts the baseplate 720, such that the central structure 711 prevents an excessivecompressive force from overloading and potentially damaging the loadcell.

Furthermore, as shown in FIG. 7G, a flex circuit 752 (or ribbon cable,or other suitable wiring) may be configured to communicate with and/orpower the electronics 750 shown in FIG. 7E, and may be long enough toaccommodate the range of linear movement of the ball nut guide 760(which may be similar to movement of the ball nut guide 568 describedabove with respect to FIG. 5A).

Furthermore, the compact load cell may be implemented in other parts ofthe tool driver. For example, as discussed above, the compact load cellmay be used to measure axial loads on the ball screw actuating thecarriage on the stage, or in any other portion of the tool driver orother applications in which it is desirable to measure axial loads.

Referring back to FIG. 4B, the tool carriage 400 may include one or morePCBs for mounting various sensors and electronics for the tool carriage.For example, a main PCB 482 may be disposed on one side to include motordrivers, microcontrollers, encoders for the linear axis drives and/orrotary axis drives, current sensors, connectors, etc. The main PCB 482may be split into two halves, such as a left side corresponding to theleft side of the housing and its components and a right sidecorresponding to the right side of the housing and its components.Alternatively, the main PCB 482 may include a single board (e.g.,horseshoe-shaped). Various wiring (e.g., ribbon cables) for motors suchas motor 452 a for linear drive axis 450 a, may be directed toward themain PCB 480 (e.g., along the direction W shown in FIG. 4B).

Rotary Axis Drive Carriage Variations

In another variation, a tool carriage may include a plurality of rotaryaxis drives for actuating a set of articulated movements of the endeffector and/or rotating a tool shaft around a tool axis. In somevariations, as shown in FIGS. 9A and 9B, a tool carriage 920 may beslidingly engaged with a base 910 such as with longitudinal rails 912(e.g., linear bearings). Additionally, similar to the tool carriagedepicted in FIGS. 2A and 2B, the tool carriage 920 may be configured toreceive and couple to a tool 950 having a tool shaft 954 and an endeffector disposed at the distal end of the tool shaft, where the tool950 is aligned so as to at least partially pass through a cannula 930coupled to the base 910. As shown in FIG. 9B, the tool carriage 920 mayinclude a plurality (e.g., six) of rotary axis drives 922 configured toactuate and/or position the end effector of the tool 950 relative to thebase 910. In some variations, a sterile adapter or other sterile barriermay be disposed between non-sterile drive axes of the carriage and asterile surgical tool. Exemplary variations of sterile adapters aredescribed in U.S. Provisional Patent Application No. 62/436,957 filedDec. 20, 2016, U.S. Provisional Patent Application No. 62/436,965 filedDec. 20, 2016, U.S. Provisional Patent Application No. 62/436,974 filedDec. 20, 2016, and U.S. Provisional Patent Application No. 62/436,981filed Dec. 20, 2016, each of which is incorporated herein in itsentirety by this reference.

Rotary Axis Drive Carriage Architectures

In one variation as shown in FIGS. 10A and 10B, a tool carriage 1000 mayinclude six rotary axis drives arranged in two rows (extendinglongitudinally along the base) that are slightly staggered (e.g., toreduce width of the carriage and increase the compact nature of the tooldriver). For example, as more clearly shown in FIG. 10B, rotary axisdrives 1030 a, 1030 b, and 1030 c may be generally arranged in a firstrow, while rotary axis drives 1030 d, 1030 e, and 1030 f may begenerally arranged in a second row that is slightly longitudinallyoffset from the first row. As another example, as shown in FIG. 34, atool carriage 3400 may include rotary axis drives arranged in anunstaggered rectangular array (e.g., six rotary axis drives arranged ina 2×3 rectangular array, or any suitable number of axis drives arrangedin a rectangular array).

As shown in FIG. 10C, the tool carriage 1000 includes a housing 1010that substantially encloses the rotary axis drives and other toolcarriage components such as one or more load cells 1040, one or morerotary axis drive output encoders 1080, wiring, and/or other suitablecomponents. For example, the housing 1010 may include a housing body1012 defining an internal space configured to receive the rotary axisdrives and other components, a bottom housing plate 1018 that couples tothe housing body 1012 to substantially seal off a lower portion of theinternal space, and a top housing plate 1020 that couples to the housingbody 1012 to substantially seal off an upper portion of the internalspace. The bottom housing plate 1018 and top housing plate 1020 maycouple to the housing body 1012 with fasteners such as screws, or may beattached in any suitable manner (e.g., interlocking features, epoxy,welding, etc.). In other variations, one or both of the bottom housingplate 1018 and top housing plate 1020 may be omitted, or may beincorporated with the housing body 1012 as an integrated unitary piece.The housing 1010 may be made of a suitably rigid metal (e.g., aluminum,steel) or plastic, and may be machined, casted, molded, or made in anysuitable combination of manners.

As shown in FIGS. 10D and 10E, the housing body 1012 may includeopenings configured to frame and otherwise provide structural supportfor the rotary axis drives and/or other components. For example, thehousing body 1012 may include an opening 1022 a configured to receiveand support rotary axis drive 1030 a. Similarly, the housing body 1012may further include additional openings 1022 b, 1022 c, 1022 d, 1022 e,and 1022 f configured to receive and support rotary axis drives 1030 b,1030 c, 1030 d, 1030 e, and 1030 f, respectively. In some variations,the housing body 1012 may include a structural framework with one ormore openings configured to provide structural support for one or moreload cells. For example, the housing body 1012 may include an opening1021 a configured to receive and support a load cell 1040 a. Similarly,the housing body 1012 may further include additional openings 1021 bconfigured to receive and support adjacent and staggered load cells 1040b and 1040 d, opening 1021 c configured to receive and support adjacentand staggered load cells 1040 c and 1040 e, and/or opening 1021 dconfigured to receive and support load cell 1040 f. In other variations,there may be a 1:1 correspondence between openings (1021 a-d, etc.) andload cells such that each opening receives and support only one loadcell (e.g., the housing body 1012 may include six separate openings forreceiving and supporting six load cells). The various openings may becircular (e.g., for supporting rotary axis drives with a generallycircular cross-section), rectangular (e.g., for supporting load cellswith a generally rectangular cross-section), or any suitable shape suchas square, elliptical, etc. Furthermore, the openings may be anysuitable arrangement corresponding to the desired (preferably compact)arrangement of rotary axis drives and other components. Although thehousing body 1012 is depicted with openings corresponding to six rotaryaxis drives and six load cells, it should be understood that the housingbody 1012 may include any suitable number of openings depending on thenumber of internal components of the tool carriage. Furthermore, thehousing body 1012 (or other suitable portions of the housing) mayinclude one or more cutouts to help reduce the overall weight of thetool carriage.

As shown in FIG. 10E, the housing body 1012 may further include one ormore mounting holes 1024 that facilitate mounting of the tool carriageto the base 1060 of the tool driver. For example, one or more mountingholes 1024 may be a clearance hole that enables passage of a threadedfastener (e.g., screw, bolt, etc.) configured to engage a threaded holein a carrier 1064 slidingly engaged with a linear bearing 1062. In otherexample, one or more carriers 1064 may include a clearance hole thatenables passage of a threaded fastener configured to engage a mountinghole 1024 which may be a blind threaded hole. Alternatively, the toolcarriage may mount to the base in any suitable manner. In one exemplaryvariation, the housing body 1012 may include eight mounting holes 1024,where two mounting holes 1024 correspond to each of four carriers 1064.Two carriers 1064 may be slidingly engaged with a left side linearbearing (e.g., a proximal carrier and a distal carrier, as shown in theside view of FIG. 10F) and two carriers 1064 may be slidingly engagedwith a right side linear bearing. As shown in FIG. 10F, the bottom plate1018 may be disposed between the bottom of the housing body 1012 and thetop of the linear bearings, in order to substantially seal off the lowerportion of the housing body 1012. Accordingly, the bottom plate 1018 mayhave clearance holes corresponding to the mounting holes 1024 of thehousing body 1012 so as to be mounted to the base 1060 with the samefasteners used to mount the housing body 1012 to the base 1060. Thebottom plate 1018 may be a thin plate (e.g., under lmm, or 0.5 mm). Insome variations, as shown in FIG. 10G, this mounting configuration mayfacilitate a clearance space 1066 located between the linear bearings1062 and under the tool carriage 1000. The clearance space 1066 may, forexample, permit passage of other components (e.g., ribbon cables or flexcables for electronic components) outside of the tool carriage or in aseparate housing compartment underneath the tool carriage 1000.Alternatively, the bottom plate 1018 may include a channel along itsmidline that drops into the clearance space 1066 for providingadditional internal volume to the bottom of the tool carriage 1000.

As shown in FIG. 10C, the top of the housing 1010 (e.g., in top housingplate 1020) may define a plurality of openings 1026 shaped and alignedwith the output of the rotary axis drives 1300 such that the output ofthe rotary axis drives may engage with a tool or sterile barrier betweenthe tool driver and the tool. For example, the openings 1026 may begenerally circular and correspond with the openings 1022 in the housingbody that support the rotary axis drives.

Furthermore, in some variations, the housing 1010 may include featuresthat accommodate assembly of one or more rotary axis drives 1300 in thehousing. For example, as shown in FIG. 10C, the housing body 1012 mayinclude a lateral slot 1015 that enables lateral insertion of one ormore components of a rotary axis drive being assembled (as furtherdescribed below with respect to FIGS. 15A and 15B).

In another variation, as shown in FIGS. 18A and 18B, multiple rotaryaxis drives 1700 may be mounted in a tool carriage housing 1790,supported by an internal chassis 1780. For example, the internalstructure 1780 may be mounted into an internal volume of the toolcarriage housing 1790 via fasteners (e.g., screws) or other suitablemechanism. The internal chassis 1780 may be formed of a suitable rigidmaterial (e.g., aluminum) and include multiple compartments configuredto receive individual torque sensor assemblies, shown in part by themultiple frames 1742 mountable in the internal chassis 1780. The frames1742 may be coupled to the internal chassis 1780, such as with fastenersapplied to the low stress points of the frames 1742. Other components ofthe torque sensor assemblies 1740 and the rest of the rotary axis drives1700 may further be assembled into the housing 1790. Overall, thehousing 1790 may generally reinforce the arrayed pack structure of therotary axis drives 1700. Although the internal chassis 1780 as shown inFIGS. 18A and 18B are conducive to a rectangular array of rotary axisdrives, it should be understood that the rotary axis drives may bearranged in a staggered, offset, or other suitable configuration.

In another variation as shown in FIGS. 38A-38E, a tool carriage 3800 ina tool driver may include a plurality of rotary axis drives that areconfigured to actuate one or more articulated movements of a surgicaltool, where the rotary axis drives are arranged in a modular, scalablearray. For example, as shown in FIG. 38A, the tool carriage 3800 mayinclude a carriage base 3410, which includes designated regions whichmay receive various modules for placement in the carriage. For example,the carriage base 3410 may include one or more drive module sites 3814a-3814 f for receiving rotary axis drive modules and/or one or morecircuit board module sites 3812 a-3812 f for receiving circuit boardmodules. Generally, the number of modules placed into the carriage basemay vary, depending on, for example, how many degrees of freedom aredesired to be actuatable by the tool driver (e.g., one degree offreedom, two degrees of freedom, three degrees of freedom, etc.). Someof the designated regions for receiving modules may remain unused, suchas if the number of drive module sites exceeds the number of rotary axisdrive modules required for a particular tool driver. Alternatively, acarriage base 3410 may be easily manufactured with fewer or moredesignated regions, such as if fewer or more rotary axis drive modules(and/or circuit board modules) are desired. For example, as shown inFIG. 38A, the drive module sites and the circuit board module sites arearranged in a rectangular array as regular, repeating rows. In differentvariations of tool drivers for actuating tools of different numbers ofdegrees of freedom, the carriage base 3810 may be shorter (with fewerrows of sites) or longer (with more rows of sites). Accordingly, therotary axis drives in a tool driver 3800 may be arranged in a modularmanner that is more easily scalable depending on the number of desireddegrees of freedom of a surgical tool that will be actuated by the tooldriver. Additionally, modularity of the rotary axis drives and thecircuit boards in the tool driver helps facilitate more streamlinedmanufacturing and/or repair of the tool driver (e.g., fewer differentkinds of parts, simpler swapping of individual modules that may bemalfunctioning, etc.).

As shown in FIG. 38A, a drive module site (e.g., any of 3814 a-3814 f)may include an output hole 3815 and one or more mounting holes 3816. Theoutput hole 3815 may receive and permit passage of a distal end of arotary axis drive module such that the output of the rotary axis drivemodule may be coupled to a surgical tool. For example, a rotary outputshaft of the rotary axis drive module may extend through the output hole3815. The one or more mounting holes 3816 may enable coupling of therotary axis drive module to the carriage base, such as with fasteners.Although each drive module site is shown in FIG. 38A as including fourmounting holes that are equally distributed at corners of the drivemodule site, it should be understood that a drive module site mayinclude any suitable number of mounting holes arranged in any suitablepattern (e.g., depending on the footprint shape of the rotary axis drivemodule). Generally, a distal portion (e.g., near the rotary outputshaft) of the rotary axis drive may be coupled to the carriage base 3810via the mounting holes 3816 at its respective drive module site.Accordingly, in some variations, the rotary axis drive may be mounted tothe tool carriage only at a distal portion of the rotary axis drive andmay otherwise be free-standing (e.g., without a surrounding lattice orframe to support the main body of the rotary axis drive). In thesevariations, the single-end mounting of the rotary axis drives mayfurthermore enable the rotary axis drives to be more easily replaced orswapped (e.g., for maintenance or repair). Additionally, the absence ofadditional supporting framework parts may reduce the number of partsthat must be modified for scaling the tool driver to include fewer ormore rotary axis drives, thereby further contributing to the scalabilityof the tool driver.

As shown in FIG. 38A, a circuit board module site (e.g., any of 3812a-3812 f) may include an interface for coupling to a circuit boardmodule. For example, as shown in FIG. 38B, a circuit board module 3850 amay include a circuit board support 3852 a and one or more circuitboards coupled to the circuit board support 3852 a. The circuit boardsmay include, for example, motor driver electronics, sensor electronics,memory, and/or any suitable electronic components that may be associatedwith a rotary axis drive module. The circuit board support 3852 a(pictured in FIG. 38B) may couple to its own respective circuit boardmodule site 3812 a (pictured in DIG. 38A) via fasteners or any suitablemechanism. Additionally or alternatively, one or more circuit boards maycouple directly to a circuit board module site via pin connectors or thelike. In some variations, each circuit board module (e.g., 3850 a and3850 b) may be associated with a respective rotary axis drive module(e.g., 3830 a and 3830 b), and each circuit board module may be coupledto the carriage base 3810 adjacent to or near their respective rotaryaxis drive modules.

The drive module sites and the circuit board module sites may bearranged on the carriage base in a regular, repeating pattern. Forexample, as shown in FIG. 38A, generally each circuit board module maybe associated with a respective rotary axis drive module (e.g., sixcircuit board module sites 3812 a-3812 f and six drive module sites 3814a-3814 f), and rows of drive module sites may alternate with rows ofcircuit board module sites. Accordingly, the rotary axis drive modules3830 a-3830 f may alternate with the circuit board modules 3850 a-3850 fin a regular, repeating pattern.

Further details of the modularity and assembly of an exemplary variationof a tool carriage 3800 with six rotary axis drive modules is shown inFIGS. 38A-38E. As shown in FIG. 38A, two rotary axis drive modules 3830a and 3830 b may be mounted to their respective drive module sites onthe carriage base 3810, in the manner described above. The rotary axisdrive modules 3830 a and 3830 b form a first row of rotary axis drivemodules. The rotary axis drive modules 3830 a and 3830 b may haverespective cables (e.g., ribbon cables) 3842 a and 3842 b that carrysignals to and from the rotary axis drive modules, such as for controlof a motor, receiving torque sensor signals, etc. The cables 3842 a and3842 b may include sufficient extra length to provide strain relief forany movement of the rotary axis drive modules relative to the carriagebase, such as torqueing. For example, in some variations, the cables3842 a and 3842 b may include a portion that is doubled up along atleast a portion of the length of the rotary axis drive modules 3830 aand 3830 b. Additionally, a carriage PCB 3420 may be mounted to thecarriage base 3810 in a manner similar to that described above for thecircuit board modules. For example, the carriage PCB 3420 may be coupledto its own circuit board support, and the circuit board support may becoupled to the carriage base 3810 via fasteners or the like. Thecarriage PCB 3420 may, for example, include electronics for the overalltool driver, such as relating to power, wireless communication, etc.

As shown in FIG. 38B, two circuit board modules 3850 a and 3850 b may becoupled to the carriage board by connecting the circuit board supports3852 a and 3852 b to their respective circuit board module sites 3812 aand 3812 b (shown in FIG. 38A). The circuit board modules 3850 a and3850 b form a first row of circuit board modules adjacent the first rowof rotary axis drive modules. Additionally, the cables 3842 a and 3842 bfrom the rotary axis drive modules 3830 a and 3830 b may be connected tothe circuit board modules 3850 a and 3850 b. In some variations, asingle circuit board module may be associated with more than one rotaryaxis drive module. For example, a single, larger circuit board modulewith electronics associated with the rotary axis drive modules 3830 aand 3830 b may mounted to the carriage base 3810 in place of twoseparate circuit board modules 3850 a and 3850 b.

As shown in FIG. 38C, two additional rotary axis drive modules 3830 cand 3830 d may be coupled to the carriage base 3810 at the drive modulesites 3814 c and 3814 d. The rotary axis drive modules 3830 c and 3830 dform a second row of rotary axis drive modules adjacent the first row ofcircuit board modules 3850 a and 3850 b. Additionally, two additionalcircuit board modules 3850 c and 3850 d may be coupled to the carriageboard by connecting the circuit board supports 3852 c and 3852 d totheir respective circuit board module sites 3812 c and 3812 d (shown inFIG. 38A). The circuit board modules 3850 c and 3850 d form a second rowof circuit board modules adjacent the second row of rotary axis drivemodules 3830 c and 3830 d. Electronics in the second row of circuitboard modules may be associated with the second row of rotary axis drivemodules.

Similarly, as shown in FIG. 38D, two additional rotary axis drivemodules 3830 e and 3830 e may form a third row of rotary axis drivemodules adjacent the second row of circuit board modules 3850 c and 3850d. Additionally, two additional circuit board modules 3850 e and 3850 fmay form a third row of circuit board modules adjacent the third row ofrotary axis drive modules 3830 e and 3830 f. Electronics in the thirdrow of circuit board modules may be associated with the third row ofrotary axis drive modules. Thus, as shown in FIGS. 38A-38D, the rotarydrive modules may be arranged in one variation of a regular andrepeating pattern.

As shown in FIG. 38E, after six rotary drive modules 3830 a-3830 f andsix circuit board modules 3850 a-3850 f are coupled to the carriage base3810, all or a portion of the circuit board modules may beinterconnected. For example, a cable 3860 (e.g., ribbon cable) mayinterconnect the circuit board modules 3850 a-3850 f. The cable 3860may, for example, include a series of connectors arranged along itslength, located at distances along the cable 3860 corresponding to thedistances between corresponding connectors on the circuit board modules3850 a-3850 f. The connectors on the cable 3860 may mate with theconnectors on the circuit board modules 3850 a-3850 f, thereby enablingcommunication with all of the circuit board modules. Furthermore, thecable 3860 may include a connector configured to mate with a connectoron the carriage PCB 3820. Although the cable 3860 is pictured as beingdisposed along a centerline of the tool carriage 3800, it should beunderstood that the cable 3860 may be arranged in any suitable manner.

In another variation as shown in FIG. 34, a tool carriage 3400 in a tooldriver may include a plurality of rotary axis drives that are configuredto actuate one or more articulated movements of a surgical tool, wherethe rotary axis drives are arranged in a modular scalable array,substantially similar to that described above with reference to FIGS.38A-38E, except as described below. For example, rotary axis drivemodules 3430 a-3430 f and circuit board modules 3450 a-3450 f may becoupled to a carriage base 3410 in a regular and repeating pattern(e.g., an alternating manner). Each rotary axis drive module 3430 a-3430f may be similar to that described below with reference to FIGS. 37A and37B. For example, each rotary axis drive module may include a motor(e.g., 3432 b, 3432 d, 3432 f as shown) having a motor shaft, a geartransmission, and a torque sensor (e.g., 3436 b, 3436 d, 3436 f asshown). Each rotary axis drive module may be coupled to the carriagebase 3410 by mounting a distal portion of the rotary axis drive module(relative to the motor) to the carriage base 3410 via fasteners or othersuitable mechanism. For example, a torque sensor (or a mount coupledthereto) of each rotary axis drive module may be coupled to the carriagebase. Accordingly, each rotary axis drive module may be supported on thecarriage substantially only by its distal portion being mounted to thecarriage base 3410.

As shown in FIGS. 35 and 36, one or more of the rotary axis drivemodules in the tool carriage 3400 may include one or more cables 3542(e.g., ribbon cable, flex cable) including a portion that is wrappedcircumferentially at least partially around the rotary axis drive aroundan axis of rotation of the motor shaft. Such circumferential wrappingmay, for example, reduce strain on the cable as the rotary axis drivemodule rotates around the axis of rotation (e.g., in reaction torqueduring actuation). In some variations, the circumferentially-wrappedcable may be oriented generally perpendicular to the axis of rotation.In other variations, the circumferentially-wrapped cable may be orientedgenerally helical around the rotary axis drive module, such that itsdirection of wrapping has a lateral component that is perpendicular tothe axis of rotation, as well as a longitudinal component that isparallel to the axis of rotation.

Furthermore, packaging of the cable 3542 and other aspects of the rotaryaxis drive module may be designed to keep components within a smallenvelope or footprint. For example, as shown in FIG. 35, a rotary axisdrive module 3530 may include a motor 3532, gear transmission 3534, atorque sensor 3536, and a rotary drive PCB 3640. As shown in FIG. 36,the rotary axis drive module 3530 may generally have a square footprinton the carriage base 3610. The motor 3532 may have a generallycylindrical body that lies within the square footprint (e.g., inscribedwithin the footprint, or smaller), thereby leaving empty space betweenthe cylindrical body and the square footprint. As shown in FIG. 35,sensor cables 3638 for the torque sensor and/or other components maytraverse within this empty space. Additionally, the attachment locationsfor the circumferentially-wrapped cable 3542 to attach to the rotarydrive PCB 3640 and a circuit board module 3550 may be selected toleverage the empty space between the cylindrical motor body and thesquare footprint. For example, as shown in FIG. 36, a first end of thecable 3542 may be attached to the circuit board module 3550 via aconnector 3544 disposed across from a flat side of the module's squarefootprint. From the connector 3544, the cable 3542 wrapscircumferentially around the axis of the motor 3532, until a second endof the cable 3542 may be attached to the rotary drive PCB 3640 at onecorner of the module's square footprint. For example, in variations inwhich the first end of the cable 3542 is located at about the middle ofa flat side of the module's square footprint, the cable 3542 may wrap atleast about 45 degrees, at least about 135 degrees, at least 225degrees, or more (e.g., in 90-degree increments) around the rotary axisdrive so its second end may be located generally at one corner of themodule's square footprint. Other extents of circumferential wrap may besuitable, for example, for a rotary axis drive module having differentshapes, in order to reduce overall footprint volume of the rotary axisdrive module.

Rotary Axis Drives

Different exemplary variations of rotary axis drives for a tool carriageare described below.

Rotary Axis Drive with Harmonic Drive

In one variation of the tool carriage, the tool carriage includes aplurality of rotary axis drives each having a harmonic drive. Forexample, as shown in FIGS. 11A and 11B, a rotary axis drive 1100 mayinclude a motor assembly 1110, a harmonic drive 1120 coupled to anoutput of the motor assembly 1110, a load cell connector ring 1130, anda motor coupling disc 1150 configured to couple an output of the rotaryaxis drive 1100 to a tool and/or sterile adapter to a tool.

The motor assembly 1110 may include a lower motor housing 1112 and anupper motor housing 1114 which house a stator 1116 and a rotor 1118rotatable relative to the stator 1116. A PCB 1162 may be locatedadjacent to the motor assembly 1110 and include at least one motorcontroller, one or more sensors, and/or any suitable electronicsassociated with the rotary axis drive 1100. An encoder magnet 1164 maybe coupled to the rotor 1118 such that one or more encoder sensors maydetect the fluctuation of the magnetic field of the encoder magnet 1164for determining angular or rotational position of the rotor 1118 (andoutput shaft of the motor assembly 1110). The motor assembly 1110 maybe, for example, a servomotor or other suitable kind of actuator. Aharmonic drive 1120 may be coupled to an output shaft of the motorassembly 1110 and configured to increase the overall torque output ofthe rotary axis drive 1100 via strain wave gearing. Advantageously, adrive 1120 may be configured to provide a high gear ratio in arelatively light and compact volume. Furthermore, a radial bearing 1120may encircle the harmonic drive 1120 and facilitate rotational movementof the harmonic drive 1120 relative to the housing body 1012. In othervariations, other suitable gear trains may additionally or alternativelybe coupled to the output of the motor assembly. Furthermore, the outputof the harmonic drive 1120 or other gear train may be coupled to a motorcoupling disc 1150 such that the motor coupling disc 1150 (which isconfigured to engage with a tool or a sterile adapter to a tool foractuating the end effector of the tool) rotates with the output of themotor assembly 1110.

A load cell connector ring 1130 may be disposed circumferentially aroundthe harmonic drive 1120 and configured to couple the motor assembly 1110to a load cell 1140 for measurement of force and/or torque loads on themotor assembly 1110. For example, as shown in FIGS. 11C and 11D, theload cell connector ring 1130 may include a mounting tab 1134 extendingradially outward and configured to couple to a connecting feature on aload cell 1140. For example, the mounting tab 1134 may couple to theload cell via a pin and bushing arrangement. As another example, themounting tab 1134 may couple to the load cell via a radial bearing, orother suitable connection mechanism. The load cell connector ring 1130may be oriented relative to the rest of the motor assembly 1110 infacilitate any suitable positioning of the load cell. For example, asshown in FIG. 11E, the mounting tab 1134 on the load cell connector ringmay be oriented such that the load cell 1140 is generally orthogonal tothe mounting tab 1134, or one end of the load cell 1140 is tangent tothe motor assembly 1110. As another example, as shown in FIG. 11F, themounting tab 1134 on the load cell connector ring may be oriented suchthat the load cell 1140 is generally at an acute angle relative to themounting tab 1134, or a midline or other point between the two ends ofthe load cell 1140 is tangent to the motor assembly 1110. Furthermore,as shown in FIG. 11D, the load cell connector ring 1130 may furtherinclude one or more mechanical keys (e.g., one or more radial tabs orkeys 1132) for fixed relative positioning between the load cellconnector ring 1130 and the harmonic drive, such that rotational motionof the harmonic drive corresponds to rotational motion of the load cellconnector ring 1130.

An output encoder magnet may be coupled to the motor coupling disc 1150(or alternatively, the output of the motor assembly 1110 in anothersuitable manner) to measure rotational position of the output of themotor assembly. For example, as shown in FIGS. 11A and 11B, a ringmagnet 1166 may be disposed around a central region of the motorcoupling disc 1150 so as to rotate with the output of the motor assembly1110. An encoder sensor 1163 may be positioned adjacent the ring magnet1166 to measure fluctuations of the magnetic field from the ring magnet1166, as shown in FIG. 12B. In some variations, as shown in FIG. 12A,the encoder sensor 1163 may be positioned substantially in-plane withthe ring magnet 1166 to face the outer diameter of the ring magnet 1166,such as on a PCB 1162 mounted along the side of the motor assembly 1100(aligned with the rotational axis of the motor assembly 1100).Accordingly, as shown in FIG. 10D, in one exemplary variation with sixmotor assemblies, there may be provided six side-mounted PCBs 1162a-1162 f, with respective encoder sensors facing motor assemblies 1030a-1030 f, respectively. The side-mounted PCB arrangements may, forexample, help reduce overall volume of the tool carriage.

One exemplary method of assembly of one variation of the tool carriagehaving one or more instances of rotary axis drives 1100 is shown inFIGS. 13A-13E. As shown in FIG. 13A, a bearing 1122 may be placed into arotary axis drive opening in the housing body 1012 and a load cellconnector ring 1130 may be inserted laterally through a slide slot 1015in the housing 1012. Thereafter, a harmonic drive 1120 may be placedinto the bearing 1122 mounted in the housing body 1012 as shown in FIG.13B, and a load cell 1140 may be placed into a load cell opening in thehousing body 1012 as shown in FIG. 13C. As shown in FIG. 13D, a motorassembly 1110 may be placed and engaged with the harmonic drive 1120. Asa result, the rotary axis drive 1100 may be fully assembled within arespective rotary axis drive opening in the housing body 1012. Theprocess may be repeated for multiple instances for multiple rotary axisdrives. Finally, a side shield 1014 (e.g., as shown in FIG. 10C) maycouple to the housing body 1012 so as to cover the side slot 1015,thereby contributing to enclosing the rotary axis drives within the toolcarriage. Other methods of assembly are envisioned, such as assemblingthe rotary axis drive outside of the housing body 1012 and placing(e.g., dropping in) the entire assembled rotary axis drive into arespective opening in the housing body 1012.

Rotary Axis Drives with Planetary Gear Train

In another variation of the tool carriage, the tool carriage includes aplurality of rotary axis drives where at least one has a planetary geartrain coupled to the output of a motor assembly. For example, as shownin FIGS. 14A-14C, a rotary axis drive 1400 may include a motor assembly1410, a planetary gear train with at least a first planetary gear stage1420 coupled to an output of the motor assembly 1410, a torque sensor1430 coupled to an output of the planetary gear train, and a compliantmotor coupling disc 1450 configured to couple an output of the rotaryaxis drive 1400 to a tool and/or sterile adapter to a tool. Thecompliant motor coupling disc 1450 may be spring-loaded to be biaseddistally by at least one spring 1452, but may adjustably move proximallyupon a proximally-directed force (e.g., engagement with a tool orsterile adapter to a tool).

Like the motor assembly 1110, the motor assembly 1410 may include astator 1416 and a rotor 1418 rotatable relative to the stator 1416, andany suitable housing components to at least partially enclose the statorand/or rotor. An input encoder 1464 may be disposed to measure angularor rotational position of the rotor 1418 (and output shaft of the motorassembly 1410). The motor assembly 1410 may be, for example, aservomotor or other suitable kind of actuator.

At least a first planetary gear stage 1420 may be coupled to an outputshaft of the motor assembly and be configured to increase the torque ofthe motor assembly 1410 by a prescribed amount in accordance with thegear ratios of the first planetary gear stage 1420. Furthermore, in somevariations, a second planetary gear stage 1422 may be coupled to theoutput of the first planetary gear stage 1420 to further increase theoutput torque. A torque sensor 1440 may have a bore that receives arotary output coupler assembly 1430, such that the torque sensor 1440 isconfigured to measure torque loads on the motor assembly 1400.

As shown in FIG. 14C, the rotary output coupler assembly 1430 mayinclude a motor coupling disc 1450 connected to a motor coupling shaft1451, where the rotary output coupler assembly 1430 is coupled to theoutput shaft of the motor assembly and is configured to move in bothrotational and translational manners. For rotational motion, the motorcoupling disc 1450 may be coupled to the output of the planetary geartrain via a drive pin 1454 operating similar to a mechanical key, suchthat the motor coupling disc 1450 rotates with the output of theplanetary gear train. An output encoder 1466 may be disposed proximatethe motor coupling disc 1450 to measure angular or rotational positionof the motor coupling disc 1450. For translational motion, the rotaryoutput coupler assembly 1430 may be coupled to one or more springs 1452(e.g., multiple springs circumferentially distributed around the motorcoupling shaft 1451) for biased linear movement toward an extended,tool-engaging position. For example, one or more pre-loaded compressionsprings 1452 may be coupled to the coupler assembly 1430 with retainingrings or other suitable mechanism. The one or more springs 1452 may beconfigured to urge rotary output coupler assembly 1430 outwards to anextended position, and one or more linear bearings 1451 (e.g., bushingor sleeve bearing) may be provided to reduce friction of thistranslational movement. The one or more springs 1452 may make the rotaryoutput coupler assembly 1430 compliant in an axial direction asindicated by the arrow C in FIG. 14B and in a comparison of the positionof the motor coupling disc 1450 in FIGS. 14A and 14B. The extendedposition of the rotary axis drive output coupler may provide apre-determined distance of compliance (e.g., 3-4 mm) that may, forexample, be conducive for engaging with the input of a surgical tooland/or sterile barrier located between the tool driver and the tool,etc.

In another variation of the tool carriage, the tool carriage includes aplurality of rotary axis drives, wherein at least one rotary axis driveincludes a motor with a hollow rotor and a planetary gear transmissionat least partially disposed within the hollow rotor. For example, asshown in FIGS. 15A and 15B, a rotary axis drive 1500 may include a motorwith a hollow rotor shaft 1516 encompassing a planetary gear box insidethe motor. As a result, the overall length of the rotary axis drive 1500along the axis of rotation is reduced, relative to conventionalmotor-gear train drives in which the gearbox is located outside of themotor. Therefore, the packaging size of the rotary axis drive is greatlyreduced while still providing desired torque increase, which may beadvantageous for the tool driver by ceding room for additional sensors(e.g., torque/force sensors, encoders, etc.), mechanisms (e.g.,couplings), or other components. Reduction of size of the rotary axisdrive also may reduce the overall volume of the tool driver and/oroverall robotic system (e.g., arm manipulator and tool driver system) toenable increased patient access and reach in the application of roboticsurgical systems, and/or may reduce mass and inertia, thereby improvingthe performance of a robotic system in which the rotary axis drive isimplemented.

As shown in the longitudinal cross-sectional view of FIG. 15A, therotary axis drive 1500 may include a motor (e.g., frameless, brushlessDC servomotor) including a housing (e.g., lower housing 1510 and upperhousing 1512 in combination) forming an internal volume. Disposed in theinternal volume may be the rest of the motor and at least some of thegear train components, such as an annular stator 1514 mounted in thelower housing 1510, an annular rotor magnet 1515 nested within thestator 1514, and a hollow rotor 1516 nested within the annular rotormagnet 1515 such that the rotor 1516 is configured to rotate relative tothe stator 15145 given suitable manipulations of the rotor magnet 1515.The hollow rotor 1516 may be supported in the housing at a proximal endby a first radial bearing 1517 and at a distal end by a second radialbearing 1518. Outer races of the first radial bearing 1517 and thesecond radial bearing 1518 may be coupled (e.g., by press-fit) to thelower housing 1510 and the upper housing 1512, respectively, while theinner races of the first and second radial bearings 1517 and 1518 may becoupled to the rotor shaft. Accordingly, the rotor shaft 1516 may befree to rotate around a longitudinal axis relative to the stator 1510and housing.

At least one planetary gear stage disposed inside the rotor shaft 1516may include an annular gear 1522, a sun gear 1516, and a plurality ofplanet gears 1524 supported by a carrier 1526. The annular gear 1522 forthe one or more planetary gear stages is coaxial with the motor andserves as a fixed reference for the planetary gear stages. The annulargear 1522 may include a flange that couples the annular gear to theupper housing 1512, though the annular gear 1522 may additionally oralternatively be fixed to the housing in any suitable manner. Theannular gear 1522 may have a hollow shaft extending from the flange,where the internal surface of the hollow shaft has gear teeth and theexternal surface of the hollow shaft is sized such that there is aphysical clearance (i.e., no touching) between the hollow shaft of theannular gear 1522 and the rotor shaft 1516. The sun gear 1516 may bemounted at a proximal or base end of the rotor shaft 1516 (e.g., mountedto a bottom wall 1511 of the rotor shaft) to be centered within andco-axial with the rotor shaft 1516. The sun gear 1516 may rotatecoaxially within the rotor shaft 1516, for example, around a supportingmember 1512. A plurality of planet gears (e.g., three or more) travelingon a carrier 1526 may be configured to engage with the annular gear 1522and the sun gear 1516. For example, as shown in FIG. 15B, the planetgears 1524 a, 1524 b, and 1524 c may be about equally distributed aroundthe sun gear 1520 (e.g., arranged about 120 degrees from one another),and simultaneously engage the annular gear 1522 and the sun gear 1520.The sun gear 1520 is an input to the gear train (e.g., by receiving theoutput or the rotational motion of the rotor 1516), while the planetcarrier is the output of the gear train (e.g., by rotating as a resultof the movement of the planet gears 1524 a-c engaging with the sun gear1520).

A second planetary gear stage may be additionally disposed inside therotor shaft 1516 and chained with the first planetary gear stage. Forexample, the second planetary gear stage may include a second sun gear1530 and a second plurality of planet gears 1534 supported by a secondcarrier 1536. The second sun gear 1530 may be coupled to the firstplanet carrier 1526 output of the first planetary gear stage and may besupported by a second sun gear support member 1531. The second pluralityof planet gears 534 may be configured to engage the annular gear 1522and the second sun gear 1530, such that the second carrier 1536 becomesthe output of the second planetary gear stage. Third, fourth, and othersuitable additional planetary gear stages may further be placed inseries with the first and second planetary gear stages in a similarmanner.

In the final planetary gear stage, the last planet carrier may becoupled to an output shaft 1550, which is supported by a radial bearing1540 facilitating rotational motion relative to the annular gear 1522.In some variations, the outer race of the bearing 1540 may be fixed to acounterbore in the annular gear via a clamp (not shown). The radialposition of the output shaft 1550 relative to the bearing 1540 may, forexample, be fixed by a combination of the second gear support member1531 urging the output shaft 1550 distally, and a spring washer (notshown) urging the output shaft 1550 proximally. Other support mechanisms(e.g., shims, shim washers, thrust bearings, compression springs, etc.)may be included to support the various planetary gear stage componentsand/or other components of the motor assembly. For example, the planetgears may be supported on pins retained in place via retaining rings,though screws, bearings, and/or other fasteners may additionally oralternatively be used.

In some variations, a magnet for an on-axis magnetic encoder (e.g., ringmagnet or ring-shaped optical encoder) may be coupled near the proximalend of the motor assembly for determining the rotational position of therotor shaft 1516. For example, such a magnet or encoder 1560 may bedisposed on the lower (more proximal) side of the first bearing 1517 formeasuring input rotation of the motor assembly. Additionally oralternatively, in some variations, the motor assembly may include one ormore sensors (not shown) disposed around the output shaft (e.g., aroundthe support bearing 1540, above the flange of the annular gear 1522),such as a reaction torque sensor, output rotary encoder, etc.

Although the variation depicted in FIG. 15A includes the sun gear asdriving input while the annular gear is a fixed reference, in othervariations, the various gear components may be driven and fixed in anysuitable combination to provide a suitable output of the planetary gearstage. For example, the annular gear may be the driving input while thesun gear is a fixed reference. As another example, the sun gear may bethe driving input while the carrier is a fixed reference. As yet anotherexample, the annular gear may be the driving input while the carrier isa fixed reference.

Rotary Axis Drive with Cycloid Transmission

As shown in FIGS. 16A-16E, in another variation of the tool carriage, atool carriage 1600 may include one or more of rotary axis drivesincluding a cycloid transmission. A cycloid transmission may enable thetool carriage and tool driver to have a low profile in a compactconfiguration of rotary axis drives (e.g., reduced length of the rotaryaxis drives measured along the axis of rotation). In some variations,for example, a rotary axis drive including a cycloid transmission asshown in FIG. 16A-16E may have a length of between about 13 mm and 20mm, or between 15 mm and 17 mm. As described above, benefits of areduced volume of tool driver and/or overall robotic system aredescribed above may include provision of room for additional sensors,mechanisms, or other components, as well as advantageously enableincreased patient access and reach due to reduced system volume, andimproved system performance due to reduced mass and inertia.

As shown in FIGS. 16A-16C, a tool carriage 1600 may include a pluralityof rotary axis drives, such as six rotary axis drives. The rotary axisdrives may be staggered or may be arranged in a grid-like fashion asshown in FIG. 16A. Furthermore, the tool carriage 1600 may include anysuitable number of rotary axis drives (e.g., fewer than six, or morethan six). The rotary axis drives may be mounted on, for example, abottom housing plate 1640 or other suitable base. As shown in FIG. 16E,at least one of the rotary axis drives 1610 includes a motor 1612 and acycloid transmission (including a ring gear 1624 and a planet gear 1622engaged with the ring gear 1624. The motor 1612 may be, for example, aframeless DC servomotor, but may alternatively be any suitable actuator.

The cycloid transmission may be coupled to or integrated with the outputof the motor 1612. The cycloid transmission is a single stage reductiontransmission that may be used to reduce the profile of the rotary axisdrive without sacrifice in gear ratio for increased torque output of therotary axis drive. The cycloid transmission may include an eccentric,rotating planet gear 1622 engaged with a ring gear 1624, while the motor1612 may include a rotating rotor 1614. In some variations, the rotor1614 may be hollow and include a bore, and the planet gear 1622 may bedisposed in the bore of the 1614, thereby further reducing the profileof the combined motor 1612 and cycloid transmission.

However, a cycloid transmission typically requires a mechanism torectify misalignment in a drive coupling due to the rotational movementof the eccentric planet gear 1622 in the cycloid transmission. In orderto rectify such misalignment, the drive coupling that couples the outputof the cycloid transmission to a tool (or sterile barrier of a tool) mayinclude an Oldham coupling. For example, in some variations, the toolcarriage depicted in FIGS. 16A-16C may be configured to actuate asurgical tool coupled to the tool driver through a sterile adapterdisposed between the non-sterile drive axes of the tool carriage and thesterile surgical tool. In such variations, as shown in FIG. 16E, therespective drive discs 1630 in the sterile adapter may include an Oldhamcoupling 1632 for rectifying movement of the planet gear. Byincorporating an Oldham coupling in the sterile barrier itself, aseparate Oldham coupling and output bearing assembly (typically seencoupled to the output of conventional cycloid transmissions) need not beincluded, thereby further reducing the height and overall volume of thetool carriage 1600.

Rotary Axis Drive with Torque Sensor

As shown in FIGS. 17A and 17B, in another variation of the toolcarriage, the tool carriage may include one or more rotary axis drives1700 having a motor 1710, a transmission 1720 (e.g., harmonic drive)coupled to an output of the motor 1710, and a torque sensor assembly1740 which is integrated with the transmission 1720 (e.g., harmonicdrive, planetary gear train, etc.) as described below with respect toFIGS. 23A-23F. The torque sensor assembly 1740 may be configured, forexample, to measure reaction torque experienced by the rotary axis drive1700. The rotary axis drive 1700 with integrated torque sensor assembly1740 may result in a more compact, low-profile tool carriage. Exemplaryvariations of torque sensor assemblies are further described below.

FIGS. 19A and 19B depict another variation of a rotary axis drive 1900that is similar to rotary axis drive 1700, except rotary axis drive 1900may include additional features for thermal management purpose. Forexample, like rotary axis drive 1700, rotary axis drive 1900 may includea motor, a transmission 1960 (e.g., harmonic drive) coupled to an outputof the motor, and a torque sensor assembly 1940 similar to torque sensorassembly 1740 described above. The motor may include a stator 1950, arotor shaft 1952, and a rotor magnet 1956 configured to induce rotationof the rotor shaft 1952 relative to the stator 1950. The rotor shaft1952 may be supported by a proximal support bearing 1960 and a distalsupport bearing 1962 positioned as far apart as possible so as to helpmaintain the axial alignment of rotor shaft 1952 within the motor.Clearance between the rotor magnet and the motor housing may help avoideddy current losses for the motor. Electronics for control of the rotaryaxis drive 1900 (e.g., motor driver, power, etc.) may be located on amotor PCB 1990 coupled to the proximal end of the rotary axis drive1900, or alternatively in any suitable location. Additional features tohelp increase cooling of the rotary axis drive 1900 may include, forexample, a fan 1954 coupled to the rotor shaft to help circulate airwithin the motor body, fins 1951 on the external surface of the stator1950, and/or cavities on the stator 1950 or other components of themotor that may receive thermal conductive epoxy.

In another variation, a rotary axis drive 1900′ shown in FIGS. 20A and20B may be similar to the rotary axis drive 1900, except that the rotaryaxis drive 1900′ further incorporates an input rotary encoder 1980 fordetermining rotational position of the motor. The encoder 1980 may bedisposed at the proximal base of the motor and be connected to the motorPCB 1990 via a flex cable 1982, ribbon cable, or other suitable wiringconnection. As shown in FIG. 20C, the encoder 1980 may include anencoder base 1984 supporting an encoder sensor 1986 configured to detectchange in magnetic field induced by an encoder magnet (encoder magnet1987 shown in FIG. 20A) on the base of the rotor shaft 1952 or near thefan 1954. In some variations, there may be a sufficient amount ofphysical clearance between the encoder magnet 1987 and the proximalbearing 1960 to reduce the influence of the encoder magnet's magneticfield caused by the rotating bearing 1960. The encoder base 1984 may bemade of a polymer or other suitable material (e.g., PEEK, ULTEM, etc.)that is suitable for handling high temperatures. Furthermore, theencoder base 1984 may include one or more cutouts 1988, which mayprovide ventilation and air circulation for cooling purposes.

In another variation as shown in FIGS. 37A and 37B, the tool carriagemay include one or more rotary axis drives 3700 having a rotary outputshaft configured to actuate one or more articulated movements of asurgical tool, such as via an output coupler 3792 coupled to the distalend of the rotary output shaft. The rotary axis drive 3700 may include amotor 3770 having a motor shaft 3776, a gear transmission 3760, and atorque sensor 3740 disposed between the gear transmission and a distalend of the rotary output shaft. The torque sensor 3740 may be configuredto measure torque applied to the rotary axis drive 3700, such asreaction torque during actuation. Various other aspects of the rotaryaxis drive may help enable the torque sensor 3740 to be includedproximal to the distal end of the rotary output shaft (e.g., proximal tothe output coupler 3792), as described below.

For example, the motor 3770 may include a hollow motor shaft 3776, andthe gear transmission 3760 may be at least partially disposed within themotor shaft to reduce longitudinal length of the rotary axis driveattributable to the gear transmission 3760. For example, as shown inFIGS. 37A and 37B, the motor 3770 may include a rotor 3774 configured torotate relative to a stator 3772. The central axis or motor shaft of therotor 3774 may include a lumen configured to receive at least a portionof the gear transmission 3760, such as an input shaft of the geartransmission. In some variations, the gear transmission 3760 is aplanetary gear train, and at least a portion of an input sun gear 3762(e.g., a shaft of the gear 3762) may be disposed within the lumen of themotor shaft 3776, such as via press-fit, epoxy, etc. Thus, the input sungear 2562 rotates as the rotor 3774 and the motor shaft 3776 rotate. Thegear transmission 3760 increases the torque provided by the motor 3770,such as due to gear ratios accommodated by the planetary gears 3763,outer ring gear 3763, and output sun gear 3766. The output of the geartransmission (e.g., shaft of output sun gear 3766) may be coupled to therotary output shaft 3790, such that the resulting torque is communicatedto the output coupler 3792. In other variations, more of the geartransmission 3760 may be disposed within the motor shaft (e.g., similarto that described with reference to FIGS. 15A and 15B) to further reducelength of the rotary axis drive.

The rotary axis drive may, in some variations, further include anencoder 3730 configured to measure a rotational position of the rotaryoutput shaft. For example, the encoder 3730 may include one or more Halleffect sensors configured to measure changes in magnetic field generatedby an encoder magnet 3732 disposed on the rotary output shaft 3790. Asthe rotary output shaft 3790 changes in rotational position, the encoder3730 may generate a signal from which rotational position may bedetermined. As shown in FIG. 37A, the encoder may be disposed in arecess of the carriage base 3710, so as to not add additional length tothe rotary axis drive 3700 when mounted in the carriage base 3710.

In some variations, at least a portion of the rotary output shaft 3790may be configured to move axially along the axis of rotation of therotary output shaft. For example, the rotary output shaft 3790 mayinclude or be coupled to a spring-loaded, axially movable componentsimilar to that described above with reference to FIGS. 8B and 8C. Inthese variations, the encoder magnet 3732 may be disposed on theaxially-movable component such that the encoder magnet 3732 movesaxially along with the axial movements of the rotary output shaft 3790.Accordingly the encoder 3730 may be further configured to measure anaxial position of the rotary output shaft along the axis of rotation,based on changes in the magnetic field generated by the encoder magnet3732.

Carriage Sensors

In addition to or alternative to the various sensors briefly describedabove, any one or more rotary axis drives in the tool carriage mayinclude other suitable sensor assemblies for measuring torque, reactiontorque, position, or other metrics. Such metrics may be used, forexample, for tracking position and orientation of the various degrees offreedom of an end effector on the surgical tool, and/or as force ortorque feedback in control algorithms.

Reaction Torque Sensor

In some variations, one or more rotary axis drives may include anintegrated torque sensor assembly for measuring torque on the rotaryaxis drive output (e.g., reaction torque). As shown in FIGS. 25A and25B, a rotary axis drive may include, for example, a motor 2510 and atorque sensor assembly 2500 coupled to the motor. The torque sensorassembly 2500 may include a frame 2540 having a proximal frame portion2542 and a distal frame portion 2544. The torque sensor assembly 2500may further include a first patterned conductive surface (e.g., on afirst conductive plate 2550) and a second patterned conductive surface(e.g., on a second conductive plate 2560) facing the first patternedconductive surface. One patterned conductive surface may be referencedto (e.g., registered to, fixed relative to, etc.) the proximal frameportion 2542, and the other patterned conductive surface may bereferenced to the distal frame portion 2544. Generally, as furtherdescribed below, the torque sensor assembly may be configured to providea torque measurement based on a differential capacitance between thefirst and patterned conductive surfaces.

Generally, the torque sensor may provide an accurate measurement ofreaction torque when mounted on a rotary axis drive, and in a mannerthat adds little to no additional volume to the rotary axis drive(thereby contributing to a compact envelope or package size of a tooldriver with multiple rotary axis drives). For example, at least in partbecause the frame is more flexible in rotation than in other degrees offreedom (e.g., axial compression or tension), the torque sensor isrobust against cross loads, mechanical misalignment and thermaldeformations that interfere with an accurate measurement of reactiontorque. The torque sensor frame may be mounted and/or sized (as furtherdescribed below) in such a way as to require little additional volume,thereby enabling reaction torque measurement in a compact volume.

As shown in FIG. 26A, the frame 2540 may have a proximal frame portion2542 and a distal frame portion 2544. The proximal frame portion 2542may be configured to couple to a portion of the rotary axis drive (e.g.,a gear transmission 2520 as shown in FIG. 25A, a distal end of a housingof the motor 2510, etc.). For example, the proximal frame portion 2542may be configured to couple to a portion of the rotary axis drive viaone or more fasteners (not shown) passing through one or more mountingholes 2543. Additionally or alternatively, the proximal frame portion2542 may be coupled to a portion of the rotary axis drive via aninterlocking fit. For example, as shown in FIGS. 25B and 26B, theproximal frame portion 2542 may include one or more cutouts 2546defining a recess (e.g., square, circular, or any suitable shape) thatinterlocks in a corresponding and complementary manner (e.g., mechanicalkey) with an external projection of the transmission 2520 (or otherportion of the rotary axis drive). The distal frame portion 2544 may beconfigured to couple to an actuated object, such that the frame 2540 mayexperience reaction torque (and relative rotational movement between theproximal and distal frame portions) as the rotary axis drive actuates.

As shown in FIG. 26A, the frame 2540 may further include a plurality ofmembers (e.g., longitudinal ribs or other connecting members). At leastsome of the members may connect the proximal and distal frame portions.For example, the flexure members 2549 may connect the proximal frameportion 2542 and the distal frame portion 2544 and provide some amountof torsional flexibility such that the frame 2540 acts as a torsionalspring. In some variations, aspects of the frame 2540 may be changed tovary the overall torsional rigidity of the frame 2540 (e.g., thespring's resistance against relative twisting of the proximal frameportion 2542 and the distal frame portion 2544). For example, theflexure members 2549 may be varied in cross-sectional shape (e.g.,round, square, etc.) and/or thickness (e.g., diameter, width, etc.) inorder to increase or decrease the torsional rigidity of the frame 2540.As another example, the orientation of the flexure members 2549 may bevaried (e.g., longitudinal, helical, angled, lattice-like, etc.) inorder to increase or decrease the torsional rigidity of the frame 2540.As yet another example, the material of the flexure members 2549 and/orother portions of the frame 2540 may be varied in order to increase ordecrease the torsional rigidity of the frame 2540.

In some variations, the frame of the torque sensor may be configured totwist up to (e.g., without being stopped by mechanical stoppers) amaximum value that is below about 0.5 degrees, such as between about 0.1degrees and about 0.5 degrees, between about 0.15 and about 0.45degrees, or between about 0.2 and 0.4 degrees, etc. For example, theframe may be configured to twist up to about 0.25 degrees in eitherdirection. In some variations, the torque sensor may be configured tohave a resolution or precision of torque measurement of within about 1mNm or less, such as a resolution or precision within about 0.25 mNm andabout 0.75 mNm, etc. For example, the torque sensor may be configured tohave a resolution or precision of about 0.5 mNm.

In some variations, at least some of the members may function toposition at least one of the conductive surfaces relative to a portionof the frame 2540. For example, in the variation shown in FIG. 26B, theanchoring members 2548 may be coupled to the first conductive plate2550, such that the first conductive plate 2550 is referenced to theproximal frame portion 2542. The first conductive plate 2550 may becoupled to the anchoring members 2548 via epoxy or any suitable manner.In some variations, the anchoring members 2548 may be longer than theflexure members 2549 such that the first conductive plate 2550 (whencoupled to the anchoring members) is spaced apart from a clearancesurface 2541 (shown in FIG. 26A) on the distal frame portion 2544.Accordingly, the first conductive plate 2550 moves in tandem with theproximal frame portion 2542, and independently from the distal frameportion 2544.

The second conductive plate 2560 may be referenced to the distal frameportion 2543. For example, as shown in FIG. 26A, the distal frameportion 2543 may include one or more cutouts or recesses 2545 a and/or2545 b. The cutouts may be generally rectangular, square, trapezoidal,or any suitable shape. As shown in FIG. 26C, the second conductive plate2560 may include one or more tabs 2562 a and/or 2562 b that are shapedto interlock and engage in a corresponding and complementary manner(e.g., mechanical key) with the cutouts or recesses 2545 a and/or 2545b, respectively, of the distal frame portion 2543. Accordingly, thesecond conductive plate 2560 moves in tandem with the distal frameportion 2543, and independently from the proximal frame portion 2542.

Thus, in the variation shown in FIGS. 26A-26C, the first conductiveplate 2550 (the more proximal conductive plate relative to the motor2510 as shown in FIG. 25B) may be referenced to the proximal frameportion 2542, while the second conductive plate 2560 (the more distalconductive plate relative to the motor 2510 as shown in FIG. 25B) may bereferenced to the distal frame portion 2544. Accordingly, as theproximal and distal frame portions move in relative torsional motion,the first and second conductive plates also move in relative rotationalmotion.

The first and second conductive plates may be generally ring-shaped, butmay be any suitable shape. As described above, the first and secondconductive plates have facing patterned conductive surfaces. As shown inFIG. 27A, one of the conductive plates may be a “ground” conductiveplate 2710 including one or more conductive regions 2712 that areconnected via one or more conductive traces 2714, such that theconductive regions 2712 form a common electrical ground. As shown inFIG. 27B, the other conductive plate may be an “active” conductive plate2720 including a first plurality of conductive regions 2722 and a secondplurality of conductive regions 2726. The first plurality of conductiveregions 2722 may be conductively coupled with one or more conductivetraces 2724 (e.g., an inner ring traversing the inner circumference ofthe active conductive plate 2720) such that the first plurality ofconductive regions 2722 and the traces 2724 form a first signal channelC1. Similarly, the second plurality of conductive regions 2726 may beconductively coupled with one or more conductive traces 2728 (e.g., anouter ring traversing the outer circumference of the active conductiveplate 2720) such that the second plurality of conductive regions 2724and the traces 2728 form a second signal channel C2. The conductiveregions 2722 of the first channel C1 may be interleaved with theconductive regions 2726 of the second channel C2. The conductive regionsof the ground and active conductive plates are shown are generallylinearly-shaped or rectangular (e.g., in the shape of “strips” or“fingers”), though in other variations, the conductive regions maycurvilinear (e.g., sine waves or other curved lines) or any suitableshape. The conductive regions on each respective conductive plate may besubstantially of the same surface area and arranged in aradially-symmetric manner, which may contribute to capacitance readingsthat have the same resolution (and thus sensitivity, etc.) regardless ofrotational position.

FIG. 27C illustrates how the conductive regions of the ground conductiveplate and the active conductive plate may be positioned when thepatterned conductive surfaces are facing one another in nominal relativerotational positions. Each of the conductive regions on the groundconductive plate may be facing at least one of the conductive regions onthe active conductive plate. For example, the outlined conductive region2712 of the ground plate may face (or overlap with) at least a portionof a conductive region associated with signal channel C1 (e.g.,conductive region 2722) of the active plate and at least a portion of aconductive region associated with signal channel C2 (e.g., conductiveregion 2726) of the active plate. In some variations, when the torquesensor is in a nominal position (e.g., producing a “zero” torquereading), the conductive region 2712 of the ground plate may face abouthalf of the conductive region 2722 and about half of the conductiveregion 2726 of the active plate. In the arrangement of facing patternedconductive surfaces, relative rotational movement of ground conductiveplate and the active conductive plate causes both a shift in the amountof overlapping area between the “ground” conductive region 2712 and the“active” conductive regions 2722 and 2726, and a shift in whichparticular conductive regions are overlapping. Accordingly, relativerotation of the ground conductive plate and the active conductive platemay result in difference capacitance signals in the first signal channelC1 and the second signal channel C2. The measurable change incapacitance, or differential capacitance, may be correlated to ameasurable change in relative position. In some variations, themeasurable change in relative position may be correlated to the changein capacitance signal c₁ from the signal channel C1 and capacitancesignal c₂ from the signal channel C2 according to the differentialcapacitance relationship of position ˜(c₁−c₂)/(c₁+c₂). In other words,the capacitance values (or changes in capacitance values) may beanalyzed to determine direction and magnitude of relative rotationalmovement between the ground and active conductive plates.

With reference to FIGS. 26A-26C, in some variations, the firstconductive plate 2550 (more proximal relative to the motor) may be aground conductive plate that is registered to the proximal frame portion2542, and the second conductive plate 2560 (more distal relative to themotor) may be an active conductive plate that is registered to thedistal frame portion 2544. Accordingly, as the frame 2540 moves withrelative rotational motion between the proximal and distal frameportions (e.g., due to reaction torque as the rotary axis driveactuates), the first and second conductive plates experience relativerotational motion, thereby resulting in measurable differentialcapacitance between the first and second conductive plates. Signals fromthe signal channels C1 and C2 on the second conductive plate 2560 may beprocessed by electronics 2572 on the plate 2560 and/or passed out of thesensor via cable 2572. In other variations, the first conductive plate2550 may be an active conductive plate and the second conductive plate2560 may be a ground conductive plate.

Furthermore, in some variations, the torque sensor readings may becalibrated against environmental factors affecting capacitive signals,such as temperature and/or humidity. For example, temperature and/orhumidity compensation may be achieved by summing the readings from thetwo signal channels C1 and C2. Additionally or alternatively, anon-board temperature sensor and/or an on-board humidity sensor may beused to compensate for temperature and/or humidity changes (e.g.,according to a known or predetermined calibration curve for the sensor).Furthermore, in some variations, the sensor may additionally oralternatively include one or more reference conductive pads to directlyprovide at least one signal for calibrating the torque sensor againstenvironment factors.

In some variations, in contrast to the variation shown in FIGS. 26A-26C,the conductive plate that is more proximal (relative to the motor) maybe registered to the distal frame portion, while the conductive platethat is more distal (relative to the motor) may be registered to theproximal frame portion. For example, as shown in FIGS. 28A-28D andfurther described below, a torque sensor 2800 may include a firstconductive plate 2850 (more proximal relative to the motor) that isregistered to the distal frame portion, and a second conductive plate2960 (more distal relative to the motor) that is registered to theproximal frame portion via a coupling ring 2880.

FIG. 28B illustrates a variation of a frame 2840 that is substantiallysimilar to the frame 2540 described above with reference to FIG. 26A,except as described below. The frame 2840 includes a proximal frameportion 2842 and a distal frame portion 2844, with a plurality offlexure members 2849 and a plurality of anchoring members 2848. Thedistal frame portion 2844 is configured to couple to the firstconductive plate 2850 (more proximal relative to the motor). Forexample, the first conductive plate 2850 may be configured to rest on aplate mount surface 2843 on the distal frame portion 2844, and mayinclude one or more tabs that interlock and engage with one or morecutouts on the distal frame portion 2844 in a corresponding andcomplementary manner (e.g., mechanical key), similar to that describedabove. The proximal frame portion 2842 is configured to couple to thesecond conductive plate 2860 (more distal relative to the motor). Forexample, as shown in FIG. 28A, a coupling ring 2880 may couple toanchoring members 2848 (e.g., with epoxy or in another suitable manner)and to the second conductive plate 2860 (e.g., with interlocking partsbetween the tabs 2882 on the coupling ring and correspond cutouts on thesecond conductive plate 2860, similar to a mechanical key).

Exploded front and rear perspective views of the torque sensor 2800 areshown in FIGS. 28C and 28D, respectively. Although these figures depictthe first conductive plate 2850 as being an active conductive plate(with a mount portion 2852 providing on-board mounting of electronics2870) and the second conductive plate 2860 as being a ground conductiveplate, it should be understood that in other variations, the firstconductive plate 2850 may be a ground conductive plate and the secondconductive plate 2860 may be an active conductive plate.

In another variation, as shown in FIGS. 23A-23D, a reaction torquesensor 2300 may be integrated into a rotary axis drive for measuringtorque on the rotary axis drive output. The torque sensor 2300 may, forexample, include a frame 2340, and at least a first conductive plate2350 and a second conductive plate 2360 adjacent to and facing the firstconductive plate 2350 in a similar manner as that described above withreference to FIGS. 27A-27C.

As shown best in FIG. 23D, the frame 2340 may include a proximal frameportion 2372, a distal frame portion 2374, and a plurality of members2344 (e.g., longitudinal ribs or other connecting members) connectingthe proximal and distal frame portions. The members 2344 preferablyprovide the frame 2340 with some amount of torsional flexibility suchthat the frame 2340 acts as a torsional spring. Alternatively, the frame2340 may omit the members 2344 (e.g., be substantially similar to asleeve). As shown in FIG. 23A, the frame 2340 may be coupled to atransmission 2320 on a motor assembly 2310 or other portion of therotary axis drive. For example, the proximal frame portion 2372 mayinclude one or more cutouts defining a recess that interlocks with theexternal shape of the transmission 2320 (e.g., square, or other suitablepolygonal shape), such as with tabs 2348 engaging the square sides ofthe transmission 2320. Alternatively, the frame 2340 may be coupled tothe external surface of the transmission 2320 or other suitablereference structure (e.g., motor housing) in any other suitable manner(e.g., fasteners). On the other end of the frame 2340, the distal frameportion 2374 may be configured to receive the first conductive plate2350 and the second conductive plate 2360. Generally, the frame 2340 maybe made of an electromagnetic shielding material (e.g., aluminum) thathelps shield the sensor from noise.

As shown in FIGS. 23A, 23E, and 23F, in some variations, the frame 2340may “wrap around” or be mounted over the transmission 2320, and theframe 2340 may be sized to have an outer diameter that is no larger (ornot significantly larger) than the motor assembly 2310 and a length thatis no longer (or not significantly longer) than the transmission 2320.Accordingly, the torque sensor assembly 2300 may advantageously becombined with a motor and transmission assembly in a manner that avoidsadding extra length and/or width to the overall package size of themotor and transmission assembly.

As shown in FIGS. 23B and 23C, the first and second conductive plates2350 and 2360, respectively, may be ring-shaped so as to be arrangedaround the transmission 2320, and include patterned conductive regions.First and second conductive plates may, for example, be ground andactive conductive pads, similar to that described above with referenceto FIGS. 27A-27C. The patterned conductive faces, as shown in FIGS. 23Aand 23C, may be adjacent and facing one another when received in theframe 2340. The first and second conductive plates 2350 and 2360 may bearranged in either order on the frame 240. For example, as shown in FIG.23E, the first conductive plate 2350 may be more proximal on the torquesensor assembly 2300 than the second conductive plate 2360.Alternatively, as shown in FIG. 23F, the first conductive plate 2350′may be more distal on the torque sensor assembly 2300′ than the secondconductive plate 2360′.

The first conductive plate 2350 may be configured to couple to anexternal surface of the transmission, while the second conductive plate2360 may be configured to fixedly engage with the distal frame portion2374. For example, as shown in FIG. 23E, the first conductive plate 2350may be coupled to an external surface of the transmission 2320 (e.g., ata distal end of the transmission 2320) such that the first conductiveplate 2350 rotates (if at all) with the portion of the transmission 2320to which it is attached. Additionally, in this example, the secondconductive plate 2360 may be fixedly engaged with the distal frameportion 2374, such as with radially extending tabs 2362 thatcomplementarily engage with cutouts 2341 on the distal frame portion2374. Alternatively, the first conductive plate 2350 and the secondconductive plate 2360 may be coupled to the transmission 2320 and thedistal frame portion 2374, respectively, with epoxy, other fasteners, orother suitable method to enable the first conductive plate 2350 to movewith the transmission 2320 and the second conductive plate 2360 to movewith the distal frame portion 2374.

As a result of the mounting arrangement of the first and secondconductive plates, generally, the first conductive plate 2350 may befree to rotate relative to the distal frame portion 2374, while thesecond conductive plate 2360 does not rotate relative to the distalframe portion 2374. Accordingly, the first conductive plate 2350 mayrotate relative to the second conductive plate 2360. Sensor electronics2370 mounted on, or otherwise coupled to, one of the conductive platesmay provide differential measurement of the capacitance between thefirst and second conductive plates 2350 and 2360. The degree of relativerotation of the conductive plates may be inferred from the differentialmeasurement of the capacitance, and subsequently mapped to a measurementof reaction torque experienced by the frame 2340. For example, when thesensor assembly is mounted on a rotary axis drive assembly of a motorassembly 2310 and transmission 2320 (e.g., as shown in FIGS. 23A, 23E,and 23F) as described above, the sensor assembly may provide ameasurement of reaction torque experienced by the rotary axis drive, asreflected by the relative rotation of (i) second conductive plate 2360and the distal frame portion 2374 and (ii) the first conductive plate2350, the proximal frame portion 2372, and the transmission 2320 orother reference portion of the rotary axis drive.

Other variations of above-described components (e.g., conductive pads)and other components may be combined with different variations of sensorframes, etc. described herein in any suitable combination.

For example, FIGS. 29A and 29B illustrate overall and detailed views ofone variation of a ground conductive pad 2910, and FIGS. 30A and 30Billustrate overall and detailed views of one variation of an activeconductive pad 2920. Different geometric parameters may be adjusted, forexample, to reduce undesirable parasitic capacitance or other edgeeffects, and thus reduce noise and/or improve sensitivity. For example,generally, the distance between conductive regions may be increased toreduce parasitic capacitance. For example, distance between theconductive regions 2712 on the ground conductive plate 2910 may beincreased to a suitable separation distance.

Furthermore, generally, larger conductive regions may experience reducededge effects. For example, FIGS. 31A and 31B illustrate overall anddetailed views of another variation of an active conductive pad. Widerand/or longer conductive regions 3122 (forming a first signal channel)and conductive regions 3126 (forming a second signal channel) providegreater capacitive area and thus may achieve improved performance forthe torque sensor with less noise.

Additionally or alternatively, the geometry and/or dimensions of atleast some parts of the conductive plates may be selected to furthermodify the overall volume occupied by the torque sensor. For example,the conductive board 2850 shown in the variation of FIG. 28A includes anelectronics mount portion 2852 that extends radially outward from thefootprint or envelope of the frame 2840. In another variation as shownin FIGS. 32A and 32B, the conductive board 3250 may be similar to theconductive board 2850 except that its electronics mount portion 3252(with electronics 3270 disposed thereon) is oriented orthogonal to therest of the conductive board 3250, thereby reducing the overall envelopeof volume occupied by the torque sensor 3200. In yet another variation,as shown in FIGS. 33A and 33B, the conductive board 3350 may be similarto the conductive board 2850 except that its electronics mount portion3352 (with electronics 3370 disposed thereon) extends radially inward,thereby keeping the electronics mount portion 3352 within the overallfootprint or envelope of the frame 3340 (and reducing the overallenvelope of volume occupied by the torque sensor 3300). Alternatively,in some variations, the electronics may be disposed on the ring portionof a conductive board (e.g., electronics 2570 on conductive board 2550as shown in FIG. 26C).

Additionally or alternatively, in some variations, the torque sensor mayfurther include one or more stopper mechanisms that limits the extent oftwisting that the frame may undergo, thereby preventing excessivetorqueing of the sensor assembly that may damage the sensor. The stoppermechanism may be a mechanical stopper. For example, as shown in FIG.23A, the frame 2340 may include at least one ball 2346 (e.g., steel orother suitable metal or non-compliant plastic, etc.) disposed between amember 2345 d (labeled in FIG. 23D for clarity) extending from thedistal frame portion 2374 and at least one member 2345 p (labeled inFIG. 23D for clarity) extending from the proximal frame portion 2372,where the members 2345 d and 2345 p move toward each other when theframe 2340 is twisted or torqued. The ball 2346 may be sized to providephysical interference between the members 2345 d and 2345 p, therebylimiting the amount of twisting that the frame 2340 may undergo. Anysuitable number of balls 2346 or similar pins may be included. In othervariations, a U-shaped piece or stopper of other suitable shape may beinterspersed between features of the distal frame portion 2374 andfeatures of the proximal frame portion 2372 for physically limiting theextent of possible torque of the frame 2340.

As another example of a mechanical stopper mechanism, one of theproximal and distal frame portions may include an anchoring hole and theother of the proximal and distal frame portions may include a clearancehole. For example, as shown in FIG. 28B, the proximal frame portion 2842may include one or more anchoring holes 2890 p each sized to receive andcouple to a pin, such as via press fit or other interference fit, epoxy,etc. The distal frame portion 2844 may include one or more clearanceholes 2890 d each nominally (e.g., in a sensor rest state) aligned witha respective anchoring hole. The clearance holes may be slightly largerin diameter than the pin, so as to permit some twisting of the frame2840, but provide physical interference between the pin and side wall ofthe clearance hole in the event of frame twist of a certain degree,thereby limiting the amount of twisting that the frame 2340 may undergo.As shown in FIGS. 29C and 29D, the torque sensor may include two pins2892 on opposite sides of the frame 2840 (e.g., equally distributedaround the sensor so provide balanced load in the event ofover-torqueing). However, it should be understand that the torque sensormay include more or fewer pins 2892.

Capacitive Rotary Encoder

In some variations, one or more rotary axis drives may include acapacitive absolute rotary encoder assembly for determining therotational position of the motor output. For example, as shown in FIG.22A, the encoder assembly 2200 may be disposed at the distal output of agear transmission 2270 (e.g., harmonic, planetary, etc.), oralternatively the output of a motor assembly (without a transmission).As shown in FIGS. 22B-22D, the encoder assembly 2200 may include a firstconductive plate 2220 with at least three conductive regions 2222 a,2222 b, and 2222 c radially distributed around the first conductiveplate 2220 and a second conductive plate 2230 having a conductive region2232 and a ground region 2234.

For example, in one variation, the first and second conductive platesmay be generally annular plates. The three conductive regions 2222 a,2222 b, and 2222 c may be equally distributed around the firstconductive plate 2220. The conductive region 2232 on the secondconductive plate 2230 may be generally arcuate, with a semi-circularmeasurement region 2232 a. However, the measurement region 2232 a may beany suitable shape covering a portion of the second conductive plate.The two ends of the semi-circular measurement region 2232 a may beconnected by a peripheral capacitive strip 2232 b, or other capacitiveregion.

As shown in FIG. 22B, the first conductive plate 2220 may be configuredto be fixedly coupled to a reference point (e.g., housing or otherexterior surface of the transmission 2270, or a structure coupled to thehousing or other exterior surface of the transmission 2270), with theconductive regions 2222 a-c facing outward. The second conductive plate2230 may be axially aligned with the first conductive plate 2220, withthe conductive region 2232 and ground region 2234 facing the conductiveregions 2222 a-c of the first conductive plate 2220. The secondconductive plate 2230 may be fixedly coupled to the rotary output of thetransmission 2270 such that the second conductive plate 2230 rotateswith the output of the transmission 2270. For example, the secondconductive plate 2230 may couple to a top plate 2250 (e.g., withfasteners, epoxy, etc.) that is mounted to the rotary output of atransmission 2270 (or alternatively, directly to a rotary output of amotor assembly, or to a dummy gear coupled to the rotary output of amotor assembly, etc.), such as with fasteners.

As a result of the mounting arrangement of the first and secondconductive plates 2220 and 2230, the second conductive plate 2230 mayrotate (with the rotary output of the transmission 2270) relative to thefirst conductive plate 2220. As this relative rotation occurs, differentcombinations of the conductive regions 2222 a, 2222 b, and 2222 c on thefirst conductive plate 2220 are overlapped with the measurement region2232 a on the second conductive plate 2230, and to different extents.Generally, the set of capacitive measurements from each conductiveregion 2222 a, 2222 b, and 2222 c may be used to determine the angularorientation of the second conductive plate 2230 relative to the firstconductive plate 2220, which provides a determination of the angularposition of the output of the transmission 2270. For example, FIG. 22Eshows a plot of signals from each of three conductive regions: signal Acorresponding to a conductive region 2222 a, signal B corresponding to aconductive region 2222 b, and signal C corresponding to a conductiveregion 2222 c. A second conductive plate 2230 having a generallysemi-circular measurement region 2232 a may rotate relative to the firstconductive plate 2220 in the same direction. For each angular positionof the second conductive plate 2230 relative to the first conductiveplate 2220, there is a unique combination of areas of overlappingconductive regions between the first and second conductive plates. Forexample, as shown in FIG. 22E, at output angular position X signal A isabout zero (suggesting no overlap between the conductive region 2222 aand the measurement region 2232 a), and signals B and C are about 80% ofmaximum signal (suggesting about 80% of each of conductive region 2222 band conductive region 2222 c are overlapped with measurement region 2232a). As another example, at output angular position Y, signal C is atabout maximum signal (suggesting the entirety of conductive region 2222c is overlapped with measurement region 2232 a), and signals A and B areabout 30% of maximum signal (suggesting about 30% of each of conductiveregion 2222 a and conductive region 2222 b are overlapped withmeasurement region 2232 a). The signals A, B, and C may be mapped to aunique absolute output angle according to the plot in FIG. 22E for thisexemplary set of first and second conductive plates 2220 and 2230. Forother variations of first and second conductive plates with differentnumbers and shapes of capacitive regions, different plots may begenerated but utilized in the same manner to determine relativeorientation of the first and second conductive plates (and thus outputangle of the transmission, when the second conductive plate is coupledto the transmission output).

In some variations, the first conductive plate 2220 may include at leastthree conductive regions 2222 a-c in combination with the secondconductive plate 2230 having a semi-circular measurement region 2232 a.If the first conductive plate 2220 includes only two conductive regions,its bilateral symmetry results in a non-unique mapping betweencapacitive signal measurements and output angle; that is, there may betwo possible output angles for each possible combination of signalmeasurements. However, three conductive regions permits a unique mapping(i.e., 1:1) between sets of capacitive signal measurements and outputangles. In some variations, more than three conductive regions may beincluded in the first conductive plate 2220. Furthermore, the size andshape of the conductive regions on the first conductive plate 2220 mayvary suitably depending on the size and shape of the measurement region2232 a on the second conductive plate 2230.

Furthermore, in some variations, a bearing 2240 may be interspersedbetween the first conductive plate 2220 and the second conductive plate2230 to reduce friction between the relatively rotating first and secondconductive plates. As shown in FIG. 22B, for example, the bearing 2240may be a thin, annular-shaped sheet made of a suitable bearing material.For example, the bearing 2240 may be made of a material (e.g.,polytetrafluoroethylene, or TEFLON) that is low-friction and does notinterfere with the capacitance measurement between the first and secondconductive plates. The bearing 2240 may further be made of a materialthat is lightweight and durable against wear and tear.

Accordingly, generally, the capacitive absolute rotary encoder 2200described above may be used in combination with a rotary axis drive in atool carriage or other suitable motor or transmission assembly, tomeasure rotational output position. The encoder 2200 is low-profile andcompact, such that may not contribute additional height or length to amotor or transmission assembly. Accordingly, the capacitive absoluterotary encoder 2200 may advantageously be combined with a motor andtransmission assembly in a manner that avoids adding extra length and/orwidth to the overall package size of the motor and transmissionassembly. Furthermore, the capacitive absolute rotary encoder 2200 mayadvantageously be made of a relatively low number of parts, therebyfacilitating simple manufacturing and assembly. In applicationsdescribed herein, the capacitive absolute rotary encoder 2200 may beeasy to mount directly to a geared transmission (e.g., with top plate2250, etc.).

Combined Reaction Torque Sensor and Capacitive Rotary Encoder

In some variations, the above-described reaction torque sensor assembly2300 and the capacitive absolute rotary encoder 2200 may be combined ona rotary axis drive or other motor or transmission assembly. Forexample, as shown in FIGS. 24A and 24B, components of the reactiontorque assembly 2300 and the capacitive absolute rotary encoder 2200 maybe stacked together and mounted on a transmission 2402. A frame 2440with a distal frame portion 2442 may be coupled to the transmission 2402(similar to frame 2340 described with reference to FIGS. 23A-23F). Afirst capacitive plate 2410 is disposed in the distal frame portion 2442and coupled to the exterior surface of the transmission 2402 (similar tofirst capacitive plate 2350 described with reference to FIGS. 23A-23F).A second capacitive plate 2420 is fixedly engaged with the distal frameportion 2442 (similar to second capacitive plate 2360 described withreference to FIGS. 23A-23F) and is configured with conductive regions(similar to first conductive plate 2220 described with reference toFIGS. 22A-22E). A third capacitive plate 2430 (similar to secondconductive plate 2230 described with reference to FIGS. 22A-22E) iscoupled to the output of the transmission 2402, such as via mountingplate 2412. Accordingly, the conductive plates 2410 and 2420 mayfunction in combination similar to the reaction torque assembly 2300described above, while the conductive plates 2420 and 2430 may functionin combination similar to the capacitive absolute rotary encoder 2200described above. As such, the conductive plate 2420 may be a commonactive board that is shared between the torque sensor assembly and thecapacitive absolute rotary encoder.

Furthermore, generally, a rotary encoder (e.g., the capacitive absoluterotary encoder 2200 described above) may be used to measure outputposition of a motor assembly or transmission coupled to a motorassembly, in combination with another rotary encoder used to measureinput position of the motor assembly (e.g., at the rotor). In suchvariations, the input encoder may in some circumstances be used tocompensate for errors from the output encoder (or uncertainty due to alower resolution of the output encoder, etc.). For example, the inputencoder may have a higher resolution than the output encoder. If theoutput encoder reports an erroneous measurement, the input encoder maybe used to determine an output position (due to known gear ratios, etc.in the motor and transmission assembly) as long as the output encodererror is within one rotation of the motor.

Although variations of the linear axis drives, rotary axis drives,sensors, and other components are described above with respect to eithera combined axis drive carriage variation or a rotary axis drive carriagevariation, it should be understood that other variations of the toolcarriage are possible by combining any one or more of theabove-described linear axis drives with any one or more of theabove-described rotary axis drives to achieve a suitable set of axisdrives for actuating a surgical tool or instrument, and/or any of theabove-described sensors or other components. For example, any of therotary axis drives discussed above with respect to the combined axisdrive carriage variation may be utilized in a rotary axis drive carriagevariation, and vice versa. Furthermore, any of the sensors describedabove (e.g., encoders, torque sensors, etc.) may be used in any suitablecombination with any of the linear axis drive or rotary axis drivevariations discussed herein.

Controls

Generally, commands may be provided to the various drives in the tooldriver (e.g., actuation of linear or rotary axis drives in the carriage,actuation of the tool carriage on the base, etc.) via software tocontrol movement of a surgical tool coupled to the tool driver and thetool's end effector. In some variations, the software may furthercontrol the tool driver to compensate for physical changes in thecomponents of the tool driver and/or tool. For example, as the tooldriver actuates a surgical tool shaft to rotate around a longitudinalaxis by driving a cable inside the tool shaft, the length of the cableinside the tool shaft changes (e.g., shortens). This change in lengthmay cause a change in the tension force that the cable experiences,thereby putting unnecessary wear and tear on the cable. To compensatefor this change in cable length, a tool driver control system maycommand the relevant motor drives to rotate in a direction correspondingto increasing cable slack or cable length, thereby releasing tensionwhen the tool shaft is axially rolled around a rotation axis.Accordingly, throughout rotation of the tool shaft, a tool drivercontrol system may maintain a substantially constant tension on eachdriven cable.

Furthermore, in some variations, the tool driver may utilize a knownreference or “home” configuration or position of an end effector (of atool attached to the tool driver), such as to enable calibration of thetool and/or to permit the robotic system to track the configuration orposition of the end effector (e.g., the extent to which jaws are closedor open, the angle of a knife blade, etc.). For example, in onevariation, the tool driver may include position sensors (e.g., absoluteposition encoders) on the drive cables running from the actuated drives(e.g., linear or rotary axis drives), where a reference or “home”position may be saved upon startup (e.g., power on) or calibration ofthe system, after sterilisation of the tool driver (e.g., in anautoclave), or during any suitable phase of use of the tool driver. Theposition sensors may track position of the cables relative to thereference position. Alternatively, upon startup or calibration, thecables may be driven to a pre-saved reference position of the cables(e.g., stored in persistent memory), or in some variations, a modifiedor updated pre-saved reference position to compensate for slippage orcreep over time as the cable relax with use and strain.

As another example, one or more sensors (e.g., capacitive, distance,etc.) may be disposed on a surface of the cannula of the tool driversuch that when the tool is inserted in the cannula and the drive cableis tightened beyond the point of removing cable slack, the one or moresensors detect contact occurring between at least a portion of the tooland the surface of the cannula. For example, after cable slack isremoved, further movement of the cable may induce the end effector orother inserted portion of the tool to move within the cannula andcontact an interior surface of the cannula. A sensor disposed on thecontacted interior surface of the cannula may detect this contact andsave the current tool configuration as a reference or “home”configuration from which to track future positions of the cable and endeffector.

As another example, pulleys directing cables from the tool driver (e.g.,within a surgical tool) may be radially asymmetrical (e.g.,non-circular) so as to enable a specific mapping between cable positionor force and the resulting end effector pose. For example, given a knownposition and/or set of forces on a driving cable, the mapping based onone or more pulleys may be used to calculate the corresponding pose ofthe end effector of the tool.

Furthermore, the system may save a reference position for each of aplurality of uses, which may provide information on which to baseexpectations for future performance. For example, if a current detectedreference position is significantly different from an average ofpreviously detected and stored reference positions, then the system maygenerate an alert or warning that the tool driver and/or tool is notoperating as expected (e.g., indicate the need for calibration orreplacement of the tool driver and/or tool). As another example, a setof previous stored reference positions may be used to determine anexpected pattern of wear and tear (e.g., normal range of creep ofcables) in the tool driver and/or tool, and if a current detectedreference position significant deviates from the expected pattern, thenthe system may generate a warning and/or evaluate the data and providesuggestions for repair and other methods of correction or compensation.

Wireless Communication

In some variations, the tool driver may include a wireless connectionfor power and/or signal communication to and from various components ofthe tool drive. Wireless connections may be desirable, for example, whenthe tool driver is used for robotic surgery because surgical proceduresgenerally require a sterile environment, and wireless connections mayreduce or eliminate the need for finding a sterile way to use physical,wired connections to power and/or communicate signals to and from thetool driver system. For example, wireless interfaces may be useful ordesirable in surgical and other environments in which fluid,contaminants, or biological, chemical, and/or radiological agents may befound.

For example, as shown in FIG. 21A, a tool driver wireless interface 2100may be provided for transferring power and/or signal communications toand from the tool driver. A microcontroller 2110 or microprocessor(e.g., located in a robotic arm to which the tool driver is attached, orother suitable control center) may be configured to generate and controlsignals. The signals may be communicated to a near-field communication(NFC) transceiver 2112 that is coupled to the microcontroller 2110. Theelectrical signals may flow from the NFC transceiver 2112 to amodulation controller 2114 and/or amplifier 2116 for conditioning thesignals. Thereafter, the signals and power may flow from the amplifier2116 to a receive (Rx) and transmit (Tx) filter 2118, and then to one ormore antennas 2120 located on the tool driver. For example, as shown inFIG. 4B depicting one variation of a combined linear and rotary axisdrive carriage, the carriage may include a wireless antenna PCB 482 nearthe rotary axis drives 430 a and 430 b, or any suitable location on thetool carriage. As another example, as shown in FIG. 10C depicting onevariation of a rotary axis drive carriage, the carriage may include awireless antenna PCB 1090 located in a PCB slot 1016 in the housing body1012, or any suitable location on the tool carriage. Furthermore, theremay also be provided an Rx channel 2130 from the Rx/Tx filter travelingback to the NFC transceiver 2112. In some variations, at least someportions of these communications (e.g., between the Rx/Tx filter 2118and the antenna 2120) may be wired with a physical connection.

As another example, a surgical tool engaged with the tool driver mayutilize a wireless connection scheme 2100′ with a tool antenna 2140 tocommunicate through a wireless communication protocol with an antenna ina robotic arm (or other supporting system used in conjunction with thetool driver). Such a tool may be in mechanical connection with a distalend of a robotic arm, but lack a physical electronic plug or otherconnection. Instead, as shown in FIG. 21B for example, the tool antenna2140 may connect electronically to one or more of a rectifier 2142, avoltage regulator 2144, an NFC transceiver 2146, a microcontroller 2148or microprocessor, one or more sensors 2150, one or more motors, and/orother electrical components. Such a wireless scheme may enablecommunication of command and control signals and power between the tooland other parts of a robotic surgical system (e.g., tool driver, roboticarm, control console, etc.).

The foregoing description, for purposes of explanation, used specificnomenclature to provide a thorough understanding of the invention.However, it will be apparent to one skilled in the art that specificdetails are not required in order to practice the invention. Thus, theforegoing descriptions of specific embodiments of the invention arepresented for purposes of illustration and description. They are notintended to be exhaustive or to limit the invention to the precise formsdisclosed; many modifications, combinations, and variations are possiblein view of the above teachings. The embodiments were chosen anddescribed in order to best explain the principles of the invention andits practical applications, and they thereby enable others skilled inthe art to best utilize the invention and various embodiments withvarious modifications and/or in various combinations as are suited tothe particular use contemplated.

1. A tool driver for use in robotic surgery, comprising: at least onerotary axis drive for actuating one or more articulated movements of asurgical tool, wherein the rotary axis drive comprises a motor and atorque sensor coupled to the motor, wherein the torque sensor comprisesa torsional spring structure having a proximal spring portion and adistal spring portion, a first patterned conductive surface referencedto the proximal spring portion, and a second patterned conductivesurface facing the first patterned conductive surface and referenced tothe distal spring portion, wherein the torque sensor is configured toprovide a torque measurement based on a differential capacitance betweenthe first and second patterned conductive surfaces.